I have 2 kids and my DH has two. We blended when they were 9,8,7 and 3.
Yes it came up with all in various situations.
This is how we handled it:
first response on the spot: "your mom/dad is not here, I am. When your home, I play the mom/dad role, so YES, you will make your bed as I said"
Step 2: family meeting to review with the group of kids, happened every time. Whole big sit down listen to the speech "your mom/dad is not here, while your here you will listen to us and respect us as the parents" blah blah blah
Our hardest experience with it was when my daughter would get a daily phone call to make sure her and SD were on the bus, DH would call my daughter at 8am. One day he got busy and didn't call. DD was upset and SD spouted off "he should be calling me NOT YOU! He is NOT your DAD!"
and DD was SO upset, crying, said "YES HE IS! when I'm here he is my dad.
Family talk that night, DH set it strait, sorry SD but I am her Dad when she is here
It also help that my ex enforces the same philosophy, however BM is another story.

Since when do kids think that the ONLY adult they have to listen to, is their mother?

I never would have dreamed of saying this when I was young, to any adult, and my SD certainly has never said it to me.

You and your DH (or SO) need to tell her what's what, and that is, that she doesn't speak to adults that way and she is to mind you.

I don't think I've ever heard my SD say she hated anybody, not in the 20 years that I've known her. She's got her own issues, but being a hateful brat has never been one of them.

Funny enough, I have never heard this out of SD. I'm surprised, because I have been a little bossy with her at times, as with my own kids, but she hasn't muttered this. YET. Talking back and giving me attitude a few times, yes, but not this. She's 13.

I would also love to hear when others began to hear it. My SS just turned 5 and he hasn't said it like that yet. They'll be times where he asks questions or is curious about how we all fit together now that I have BS and he calls me mom instead of Max but it's never come from a place of anger or defiance. I'm sure it'll come though, my bet is 8 or 9.

I think it was when I first moved in and instituted actual rules about cleaning things up.
(discussed with DP before I moved in and agreed upon; it was a super small house)

This statement was then followed by booby-trapping or intent to destroy or damage some of my things.

Note the only SD who ever said it was SD(then 9) - SD(then 7) has never said it nor did she instigate the other issues.

A luckily short-lived phase as DP stopped it very very quickly.

My response was "No, I am not your mother, but I am an adult in the house and have responsibility for it (and you if necessary)."

My SD just turned 6. From a very young age it was told to her that I was SM her mom was her mom and her dad her dad and BM's husband was SD. She calls me mommy sometimes. But we are all in agreement of all 4 of us are the adults and make the rules in our homes. She has never said this to me, and I think it would hurt if she did. And seeing as how I have a strong personality, I like boundaries and structure, I can see how at one point in her life she may tell me "you are not my mother".

SO and I already discussed what would happen. The consequences will be quite harsh probably but she has to understand that her words can hurt people. I bathe her, I pay for half the rent in our home(even though SO and her have more space), I pay for most of the streaming programs. I make more than SO does and therefor have the luxury of having more spending money. Which I spend quite a bit on her. I do love her quite a bit, I discipline (on rare occasions, SO does all the major disciplining). I pick her up from her mom's on non-visitation days when there is a party in my family that she wants to go to. I drive her around, give her allowance, buy her toys, food, clothes. Way more than SO and her mom can. I do it all because I care about her. So the day she says anything to me in that nature...it all stops. And I am sure she will ask why it has stopped. And SO agreed that he will sit her down and explain exactly why I disengaged. It would be up to her to decide if she wants to apologize or keep with the attitude, but I will not give to a child I don't have to if the child is going to be rude to me.

I hope that day doesn't come, but I am sure it will. Lucky for us all 4 of her parents instill in her that she has to respect us all.

I am afraid of this day, although I know it will come. I always assumed during the pre-teen years with SD and hopefully never with SS, as he is a very kind soul.

No matter how prepared I am for this, it will break my heart. Stupid, I know!

My SD's were older when we met; YSD 11 or 12 but still a few years later during her teens years when she was going through not such a great stage with me she would say things like "it's not a STEP-PARENT'S PLACE to say blah blah blah" or "A STEP-PARENT has NO RIGHT to ask blah blah blah" "It's none of a step-parent's business if yada yada yada happens" and so on

Of course it was always about her friend who hated her step-parents, but considering that it was said in my presence, I figured it was meant for me too even though I had personally never done those things LOL

I handled it with disengaging from her, letting her see in subtle ways that you know what, that works two ways.

For YSD, that was the trick (this doesn't seem to work much with OSD haha)

These days, YSD very much considers me another parent, her "other mother" and she treats me very well. She has truly grown up and come around

Your skid is only six, could well be going through a stage. Don't reward that behavior. Make she knows she cannot disrespect you, but, if she is going to behave like a brat towards you there will be consequences for that

My SD did it when she was 6. I simply told her she was correct, but I am an adult and she will respect me. Never heard it again. I won't be disrespected in my own home.

Answer: “In that case get outta my way I am going home.” Then walk on by and leave her there. See how she likes that. She probably won’t like it very much.

As for the dreaded statement …. I never heard it. I am not sure if that is due to it being more of an SD thing than a SS thing or if it is due to our specific blended family dynamic. My bride and I met and started dating when SS-24 was 15mos old and we married the week before he turned 2yo. I was the first person he ever called Dad(dy) though the SpermIdiot was always in the picture.

In fact my kid always confirmed that I am his dad. Period. When his mom and I first broached the topic of my adopting him his was response was…. “You are my dad, you have always been my dad, and always will be my dad. What difference would an adoption make?” He was pretty young at that time. There was no way we could argue with his logic.

During the difficult teen boy brain fart years when his mom and I let him know that if he did not want to pull his head out, engage, and comply with our household and family behavioral and performance standards that we would allow him to move to his SpermIdiot’s his response was…… “ :? Why would I do that? This is my home. You are my mom and you are my dad. I don’t want to be anywhere else.”

We did have the REAL Dad Vs. Step Dad definition discussion a couple of times after SS returned from SpermLand visitaiton and either the SpermIdiot or SpermGrandHag had told him I was not his REAL dad or that he could not call me "dad". SS was always confused and upset by their comments on the subject.

It sounds to me that BM is planting PASing bugs in her ear. It is time to give this little girl some clarity on both the PAS BS and on the snarky manipulative crap.

“When you are with me, I am your parent.” Say “Mom” even. But… if I say that directly, some of our friendly Stalker friends get a little bunched up over it. I believe that being a Mom or a Dad has little to do with who donated the sperm or womb services and everything to do with who takes the responsibility and performs the roles and takes the actions of Mothering or Fathering. Those are the REAL Mom or REAL Dad.

But, many breeders don’t like to hear that perspective.

You and your SD will work it out. But… I would not let the comment go unaddressed.

Mom it up!!!!!!!