There's your problem:
Dad is now half of a team, & he owes you the loyalty (not to mention the respect he'd show to anybody else) to stick to your agreement.

Remind him, & insist that he follow through.

& stop trying to make this girl like you;
it hands her the power to make you feel like an outsider in your own home.

You & your husband must be the "insiders", the team, & she, like anybody else, must obey your rules when she's there.

That would include being a civil human being.

I wish you the best.

I have dealt with the struggles being a BM and DD having cheer on Saturdays that SM refused to let her go to buy my arguement was when I signed her up I called BD. Told him DD wanted to do cheer but here was
the schedule. I agreed to pay for all costs associated with it and to even
give him extra time to make up for the 2 hrs on Saturday he missed by
maybe offering my Saturday or Sunday afternoons. BD was fine with it
until SM came in the picture and said NO, BM and DD will not schedule
events on our weekends. That made me angry because he originally
agreed knowing if DD missed practice she would not get to perform. Same
with soccer. Thursday nights for two and a half months so we switched to
his night being Wednesdays. He was missing NO time with DD but SM
came in and said NO the order states Thursdays. So DD missed soccer
and cheer and has not participated in those activities since. I had to find
something that was not on the weekends and was not on Thursdays.

With that being said, does not sound like your sd's BM consulted with you at all on the activities ... So I feel you are in the right to say No we aren't running around doing what she says on our time.

I think that if BD does not stand by you and stick to your agreement you are just between a rock and a hard place. Period. You have to talk with him and let him know what he is doing and how it's making you feel. Use I statements not YOU statements like - when you don't stick to our agreement about the apology, I feel like you don't respect me as your equal. I bet he just misses SD and will do anything to get in her good graces but that just enables her bad behavior towards you.

Don't let her make you feel like an outsider. I normally would not suggest this but in your situation I think this may help you. If and when SD comes over, make plans for yourself and your DD or with friends. Allow BD and his kids time alone while you make yourself busy and unavailable. They may start respecting you more when they see it doesn't effect you and you aren't 'threatened' by their presence. You are simply respecting the father/daughter relationship by giving them one on one time. Our therapist has suggested that DD and Bd spend a couple hours without SM and without stepsister atleast once a week. That way DD gets her time with her daddy that she so desperately yearns for. And she enjoys the time with SM more because she isn't constantly there. I had a bit of a problem with this at first bc I think it's giving my DD the wrong idea that the family unit bio plus step plus half or step siblings are not a full unit but when talking to DD she says 'i don't know why but I just want to be with my daddy sometimes alone' and I just realized there is no reason for her feelings, she just feels that way... And I make sure I spend one on one time with each of my bio kids seperately so they each have special time as the 'only' child it makes sense for BD to do that as well.

Good luck. Let us know.

What is funny is that when I started doing this my guy would think I was trying to seperate myself from them. I think it was a control thing. I hated it. I wanted them to enjoy their time together because I didn't always feel like I should be there. I felt like I was invading their space sometimes and it was awkward. I didn't take offense. I just saw it as an opportunity to have "me time."

Well...I stopped doing my own thing and resentment began to build up. I hated it. I felt like a prisoner.

Needless to say...over many obstacles...this doesn't happen anymore and we are both much better together because of it.

On the weekends we get the kids BM calls my DH. He litterally has to write everything down that she tells him. SS game times, SD game times, (btw they dont speak to dad at games either if BM is around)acting class times, ect. Yes this aggravates me but he can not say "No we are doing that on our time" its the kids activity, does not matter who's time it is. They live with BM she is the one who knows thier schedules and what they have going on. And usually if they need anything, like science fair supplies, school supplies, new glasses and of that kind of stuff she will tell them to have dad get it, which he does. So I would not think to much about that part as long its legit stuff that for the kids.
I understand trying to make SK's like you. I still do this and cause myself more greif because I try so hard. I have noticed when I dont try so hard its usually a better outcome.
The advise about planning something with your DD or freind and giving dad time alone with his kids is great. We went to a stepfamily seminar and that was suggested. Just be careful of how often you take that time. I did this before we went to the seminar, I hang out in my room to get some peace (still do at times)my DH did not like this at all. He thought I was trying to get away from his kids ( I was, lol)and it hurt all thier feelings. I work every other Sat which happend to fall on the wkends we have kids, the kids got offended that I did not want to be there on Saturdays with them. I figured out they want me there. When I get home they surround me and tell me everything that happened since I've been gone. So time away is good, family bonding time is good too.
We have had a rough year, we have had really good times, and really bad times. I can say now I do love my Stepkids, I would do anything for them. The way they put it at the seminar is "Stepfamilies are like a good pot roast being cooked in a crock pot" It takes a while for it all to cook and come together but ends up better for taking the time to simmer than to cook it so fast.
I apoligize for such a long post, but when I read yours it hit home and wanted to tell you my experiences.
Good Luck!!