Oh hell no. She also has no reason to come on special occasions. 

WTF? Hell no would I play babysitter for bm's other kid.

H.E.L.L.N.O. 

I'm a BM with an ours daughter and there is no way I would expect her to go with to an ex's house.  (I wouldn't anyways).   You BM is looking for a free babysitter.  M sure SD could use a break from her little sister 

 NOPE 

My DH would laugh in his ex's face if she expected that of him. And there is no WAY I'd let that ridiculousness happen in my home. 

No just no! You're. It bms babysitter nor do you or DH have any obligation to this little girl.

Maybe if BM wanted to pay you the hourly rate for a nanny while her other child stays with you...seriously, though, the nerve of this woman. 

Before DH and BM were even divorced, BM's BF moved in with his son. BM used to ask DH to take her SS when he took his kids because she wanted to go away with her BF and DH told her "no way." 

So if you and DH had an ours child would it be ok to send it with SD when she goes back to BM? That child would be SD's sibling too. But who on earth would think it's reasonable for BM to take on her divorced husband's new kid?!

Some of these BMs really are the dregs of society. Between the girl's BD and your DH, BM probably got plenty of "me time" before you came along. She's probably collecting child support on the other kid, too, from her BD while she pawns her off. 

There is absolutely no reason for you to feel guilty.

The girl is your SD's sister but she is nothing to you or your husband and neither of you have an obligation to have her in your home. You certainly have no obligation to be BM's babysitter, and I wouldn't.

This life is hard enough on step moms without adding BM's kids from some other guy in the mix. Geez.

My DH had a step son (my SD's half brother), he has never been to my house. In fact, I've only met him once, when DH and I were first dating (we've been together 24 years).

I was okay with accepting DH's daughter (I love him, so accept her), no way was I accepting BM's son. Especially, with the crap that she pulled and the way she treated my DH. Not to mention, BM did everything she could to ruin the relationship between DH and her son.

Stand your ground.

What the heck? Now I've heard everything.

Next time she asks tell her your rate for child care is $20/hr, payable when the kid is dropped off.

Just another thought to bolster your arguement, what happens if little sis gets ill or injured? neither you or your husband are able to give medical consent.

She wants free childcare.  Crazy.  That would be a hell no from me.

Nope, its a trap.

Tell me, does she send your so's child to the other child's father too? Sweet deal... 

Nope! Don't do it! My ex when we started dating told me once "I'm losing so and so and I want to cry" which is his ex wife's oldest daughter who is NOT his. 

I should have RAN then.  She was 9 years old at the time.  His ex wouldn't even have to push or ask for him to include her or bring her with their two daughters. He offered.  She expected it of him and although I put my foot down at first and said I'm not having it. He gaslit me to believe I was wrong for doing so.  It wasn't always but if the BM ever needed a sitter while he had his daughters she was always included in my home.  An extra mouth to feed, to worry about.  I did the best I could but always knew it was wrong.

Part of me thought and still thinks he is/was still in love with the ex wife and did all that he could to show her he would still do whatever it took to save his family.  Even after the reason they weren't together was that she cheated on him numerous times and left him.

Pisses me off so bad re-thinking it.

Don't let him OR her do this to you!! It's bull shit!!

Now Ive seen everything.

OP, Im SO glad that you put your foot down! Thanks for the update because it was making me stress on your behalf.

I can KINDA, SORTA, MAYBE understand that skiddos dont want to be alone and love this other sibling a lot etc. But just the whole thing boils down to BM being a user.

The little girl isn't at fault in all this, and may not understand why she isn't welcome -- but that's the failure of her boundary-less mother. It's time she learned that her family's family isn't necessarily her family.

what ? now ive heard everything!  this is so wierd ,,, this kid has nothing to do with you and your husband . 

Lol - yeah she's 100 percent looking for a babysitter. I'm sure she has plans and is annoyed one is still at home. That's unfortunate that she's probably making the 11 year old feel bad in a situation she wouldn't otherwise think twice about, but that's on BM not you. 

Personally I have 3 kids and love getting one on one time with each, so to me this says something about her.

My ex remarried and had a daughter with his new wife.  Their daughter did and still does come to my house.  HOWEVER and this is the big huge part, it was never expected by anyone!! 

She is my son's sister and because we all got along this worked out great for us.  But again was never expected.  My family took her in and even purchased birthday and Christmas presents for her because she is my sons sister.  (We don't do half's at our house I think it is an ugly unnecessary term only used to let the world know someone is defining the relationship).

Being expected I agree is just for babysitting services.  

BM's breeding mistakes that are unassociated with your SO are not his problem, nor are they your problem.  

Time to shut down the half sister visiting your home without an invitation. If BM asks, the answer is always no. If the actual Skids ask... the default answer should be no.  Though you of course have discretion to say yes if the spirit moves you.

We never invited SS's three  younger also out of wedlock Spermidiot spawned half sibs to our home.  SS didn't want them in his real life.  Because of all of the drama associated with the Spermidiots serial statutory rape babies and all of the other shit associated with the shallow and polluted end of his gene pool he wanted to be an only child in his real life.  

However, we did offer to adopt them when thd SpermClan got all wrapped around the axle over CS, the cost of visitation travel, etc, etc, etc.....   That shut them up for a while.

Sadly, Spawn #3 just reported to prison to start serving the 5yr sentence for his felony conviction.  #4 is going down the same path.  #2 is struggling but compared to #2 & #3 she should be okay.  My SS is kicking butt.  Alone he is far more successful than all of prior generations of the shallow and polluted end of his gene pool combined.

We are very proud of him.

We never felt guilty about the shit show circus that the SpermClan lives.

Time to give BM the clear message that she does not matter and her other children do not matter during DH's COd time with HIS children.  You and DH hug his kids, tell them you are so sorry that their mother has problems, but that your home will not welcome BM's issues.

Lather, rinse, repeat.  Stay on that message.