Is It Ok Not to Invite Future Step Daughter to Be Bridesmaid?

My fiance's daughter (aged 14) has had little to do with him for the past 3years, despite huge efforts on our part. We travel to visit her & her brother every other weekend but always get blown out (unless it is around her b'day / Christmas / school trip needs paying). I have tried my absolute hardest to be kind & treat her like a friend with shopping trips etc, but, it just gets thrown back in my face. When her Dad & I arranged to meet both of them to announce our wedding (before telling other family members)- she didn't even turn up. We tried the next day,after reinforcing that we had some special news to share with her – but still no show.
After all the pain she has caused my partner by blowing him out, and being so disinterested in our wedding announcement – I really don't want her to be stood next to me as bridesmaid. How can I handle this without appearing to be the wicked step-mother / destroying all future chances of a good relationship?

Suggestion:

there is no requirement whatsoever that brides maids must include family members. your brides maids are supposed to be girls who are close to you and who share things in common. she is a little young anyway to be a brides maid. she would not be able to participate in any of the adult things sometimes associated with brides maids and their bride. she is too old to be a flower girls so her position would be as a junior brides maid if she has any and that would not require you to invite her to everything you do.

but it is really up to you who you have as a brides' maid. if you want to include her so that people do not say you left her out on purpose, give her a task like handing out the wedding programs or the bird seed, flower petals or bubbles for your departure and include a thank you for her contribution in your wedding speech or on your program.

you could have her in a dress that is the same color as your bride's maids but in a different shade of the color or in your accent color. give her a coursage and perhaps a little thank you gift for her part.

that way, she can come to the rehearsal and dinner, and be part of the wedding without actually standing up with you and casting sullenness all around.

she may not want to have anything to do with it all. have you tried asking her what is bothering her. maybe she has been hoping for her parents to get back together or something and it has left her hurt and confused….as teenagers so easily become.

anyway, you and her father need to not take it personally because it is most likely an issue going on inside her rather than anything with either of you. all you can do is try to reach her and leave the rest to her need to grow up.