openness question- with foster/adopt daughter

Would you allow your foster/adopted daughter to be a flower girl in her birthmom's wedding? My daughters birthmom just told me she is getting married in Sept and would like my daughter to be a flower girl along with the daughter she is parenting. A little background- We got my daughter at the age of 14 months and fostered her the next year and a half. Finally right before she was abotu to go home bmom tested positive for drugs and had to sign her rights away or loss her new baby as well. We've had an open adoption since then, but it has been very rocky. We've had to take a break once and almost cut-off everything but written contact back last April. But in May we talked a lot and things have been much better since. We typically have visits anywhere from a couple times a month(rare) to once every several months just depending on how we are all feeling and what we are ready for. I'm having a hard time trying to figure this one out for several reasons...but wanted to just get your opinion and find out how you would feel about it if it was your child.