So DH has 2 exes (I can already envision the judgemental comments from some 😂): two sons from ex1 and one daughter from ex2 (the BM in question).
SD always ends up with her mother on her bday, her friends are closer there, so it's normal. Her mother decided after the separation with DH 11 years ago that she will keep his sons (her ex step sons) close. Each time it's SD's bday, she invites them. She doesn't have to, because she knows that DH ALWAYS does something for SD's bday and she also has a son from previous relationship as well as new step children and SD's friends. So she does have a crowd for SD's bday.
Now, once my stepsons went to SD's party, the're not going to celebrate her again, so when it's our turn to do something with her, it's basically just DH, me and our child as well as my other son, the same people she sees when she comes to stay with us EOW. So it's much more boring for SD who clearly doesn't even make it a priority. Today is her bday, the party was yesterday and she told DH that he can come see her, but then he needs to bring her to whatever other plans she's made. Obviously when it's like this, I'm not going to come with my children, because we'll be just waiting for her to wake up late from the party (outside in the car), then driving her elsewhere.
If my stepsons were available, we could have had a bigger and nice gathering.
I know that people have the right to do whatever they want, but does it feel that BM has been overstepping all these years?