You sound like a caring person who wants the best for everyone.  But this child is difficult and you dont have to love her.  You do have to be kind and civil and make sure she is safe and fed.  It sounds like your DH is realizing that he needs to ramp up his parenting and its HIS job to make her behavior more lovable.  If he is willing to make some changes, the SD will probably improve.  She is capable of understanding that you have different standards at your house, like kids who misbehave at home often do well at school where different standards are enforced.  Keep working on him, he is the key.  Good luck.

Looks like this is a child that only her mother can love.   Let DH take on her care  and deal with her demands, tantrums ect.  You cook. Either she eats it or it's on DH   

You absolutely don't have to love this very tiresome child! Treat her kindly but very firmly, and encourage your DH to do the same, and hopefully you may be able to undo some of the worst of BM's influence, at least while she's at your house. That is the most you can hope for.

Well, I don't know if he's such a wonderful dad, since he's part of the reason she's so unlikable, but at least he's trying.

You don't have to love her, why would you feel guilty for not loving someone? That's entirely a personal thing.

You can't magically love/connect with everyone. And I think spoiled children tend to be harder to love. I used to feel guilty about not loving or even liking my SD. I assumed over time I'd become attached to her. But then I realized its not just the time spent. After all, I spent how much time with coworkers and miss some of them to this day and some I'd gladly never see again. 

Not feeling attached to your SD is ok / normal / doesn't make you a serial killer.  It must be hard, especially as you're already a parent, to want to help another child be their best and grow up safe and secure, when they just don't click with you as a person.  I certainly find it impossible, even after 4 years of inner conflict/counselling / putting aside my strong negative feelings towards my SKs. It is not your fault or responsibility to make things be right when that child has their own parents, for better or for worse.  Maybe your relationship will improve in time, over the years to come.  Even if it doesn't ,please don't spend a millisecond feeling guilty - unless you have explicitly been given unconditional parenting rights over SD, you have zero responsiblity for what happens to her, beyond basic safety and civility. Your only priorities are yourself and your own children, and to a different level, your SO.  As you say, SD has others caring about what happens to her. In my case, if my SK's relatives want to treat them like helpless invalids and permanently aged 3, incapable of normal child behaviour, good luck to them all.  Let's see how that works when the 2 mouthbreathing little idiots face the reality that Daddy isn't their slave, they need to use their own brains sometimes and life is cruel.   Save your sanity and energy, and enjoy the children you truly do love! My SK experience has made me treasure the childhood and growing up of my own DD22, and made the joy of motherhood all the more sweet. 

Between being a good dad. And a good parent.  A good parent teaches there kids to become a person. Not a baby 

How exacttly, does one feel guilty about not loving someone?  Or feel guillty about loving someone for that matter?

It is not this kid you do not love, it is her manipulative inappropriate choice of behaviors. Yes, she is 6. I get that.  However, a 6yo is clearly capable of understanding the difference between a good choice and a bad one.  So, bring misery inducing consequences to bear immediatly when she perpetrates those behaviors and explain that her choice to behave in that way will not be tolerated and she will experience immediate unpleasant consequences for that choice. 

Lather, rinse, repeat until she has cycled through her poor behavioral choices and has a demonstrated understanding of what choices return a state of immediate and durable abject misery and which choices return positive responses and pleasant responses from others.

You and her father have time to get her straightend out but not enough time to delay in forcing her to comply with established standards of behavior and performance in your home.  A remote corner for her to hold up with her nose while everyone else in the home goes about their business and enjoying each other is a great disciplinary tool for kids that choose to behave as your SKid chooses to behave.  She is also at the young end of the age where countless sentences represent a great consequence for her poor behavioral choices.   Sentences engages the ill behaved childs brain to a repetitive task that burns the message related to their choice into their brain.  We used them to great results with my SS when he was growing up.  Lying, failing to do or turn in his homework, etc, etc, etc....  We assigned him a large number of sentences (as many as 10,000 as he grew older) all in perfect handwriting, using perfect spelling, using perfect grammar, at a pace of 180/hr at any time he was home from school, family activties out of the home, or extracurricular activities.  It is key to not punish the family by limiting family activities or punnishing the family for the ill behved SD's behavioral choices.  We learned fairly quickly that limiting our family activties to accomodate the consequences for his actions was not a good idea.  So, no TV, no video or computer games, he was writing stentences from the moment he finished his homework until he went to bed, day in, day out, weekdays, weekends  until he finished his quota of sentences.  Missing an hours quota, poor handwriting, or grammatical or spelling mistakes reset the count for lower sentence assignments and a day's production for severe infractions that got him  multiple thousands of sentences.  To this day, SS-28 has the most beautiful hand writing I have ever seen any man produce.  

When we are all together and ribbing each other if the Tower (the isolated empty room he wrote sentences in) comes up in discussion he will give us crap and we all laugh heartily about those memories. The kid has a great sense of humor.  The three of us are very close. He is an only child in our family.

Idealy the goal is driving her to understand good Vs bad behavioral choices but her understanding is not required for application of effective consequences for her bad choices. The primary goal is behavioral modification.  Whether she gains clarity and undertanding or not.

If you make it purely about her chosen behaviors and filter out the feelings and emotions the path required to fix the situation will be much clearer for you.  IMHO of course.

My parents let my younger brothers and I know immediately if our behavioral choices were unacceptable.  "We love you but we don't like you very much right now. Knock it off. NOW!"  Then depending on what poor choice we had made the consequences flowed.  You know, what good parents do when raising children.

Do not focus on your feelings. Focus on her behaviors and the application of immediate consequences that stops her poor behavioral choices in their tracks each and every time she perpetrates them.   I am confident you will find that your feelings about her will change significantly and fairly quickly.  Love is not a feeling, love is action. Take the actions of love and the feelings will come.  In this case the action is immediate action in response to her poor behaviors.

And you are wrong about it not being her fault. It is her fault. BM is not standing in your home perpetrating the behaviors that SD is choosing ot perpetrate.  BM certainly has influece over SD but SD's behavioral choices are her own.  Poor choice-consequence-misery.  The sequence of events associated with behaviors that violate the family behavioral and performance standards that all children are held to in an age appropriate manner. 

Quality choice-acceptance-positive result.  The sequence of events of her choice to modify her behaviors and consistently perform to behavioral and performance standards in your home and family.

Lather-rinse-repeat on both.

It works.
Give it a try. Choosing to feel guilty solves nothing. Take action.

IMHO and experience of course.

Good luck.  

Some kids are hard to like because of Thier behavior. I have had to stuggle with this myself because I have always worked with kids and now incarcerated adults. 

I can usually find endearing qualities in most people. Even though YSD has some significant behavioral issues. She can be very sweet and kind. She is definitely immature for her age and I hope that one day she will grow out of some of it.

OSD on the other hand I can't even bring myself to be fake nice to her, so I avoid her. She is older and some people just have a bad aura about them. She is very cold and self- centered, she lacks empathy which makes it difficult to be around her. 

It's like with most narc's they are emotionally draining.

Unfortunately it sounds like in your situation if BM keeps brainwashing SD that she is the center of the universe and DD is abusive she may exit when she is old enough to do so. 

It seems there is this expectation that specifically SMs love their SKs. This isn't realistic. In your case, you did love, and probably still love, your SKs from your previous marriage and I think part of that love grew because they were the light in your abusive marriage. By the way, very proud of you for leaving that situation. But the fact that you grew to love them so much shows that you have a big heart and can find the good in a bad situation.

That said, I wouldn't love your SD either if I was in your shoes. Her BM isn't doing her any favors by wiping her ass at this age. It seems your DH is open to advice, which is a really positive thing and if he's open to your advice, you can definitely work towards a more pleasant home life when she does visit.

In the meantime, you have a wee little one and a teenager during a global pandemic. As their mom, I would focus on them. If SD wants to participate, she can. Let's say all of you want to watch a movie, or have your favorite meal for dinner and she throws a tantrum. Fine, throw your tantrum. The rest of us are going to enjoy ourselves. She'll want to be part of the group at some point and begin to calm down and join in. But do not give in to these tantrums. She's still a child and there's probably a lot going on and she's limited in how she can express herself. It will take work and a lot of frustration, but as long as you and DH can remain on the same page, she'll grow to understand that routine, structure, and responsibility are part of your home and can be a positive thing.

I have an SD too who is just about to enter her teen years and in the many years I've known her, BM has not taught her to do chores, expanded her palate, and is always making sure SD never feels a second of discomfort. I don't come from that background and my home is not going to cater to someone else's bad habits. I started making her make her bed, put dishes in the sink, take regular showers, and eating new things. She'd complain at first but I'd just remind her we don't make her do anything we don't do. We're eating this because it's dinner for all of us. You have to make your bed because we all made our beds. While she still does zero chores at home, the days we do have her, she's been making her bed before I even ask her, bathing regularly, and eating what gets put in front of her, even saying she's trying not to pick out things she doesn't like. It took a few years, and she is a bit older now, but it will improve. She even told her BM that she only makes her bed at our house, so don't expect her to do it there! That wasn't what I was going for, but the important thing for us is it established boundaries and an understanding at our home and that's all I care about with regards to my own sanity.

The love may come, it may not. Know that you are not obligated to love her. Be the best you can be, supportive, inclusive, and give her a safe space to grow with you. Even if love never develops, respect and understanding will. If the love does grow, it's a bonus for you both!