I feel for the OP, a lot.
I have dealt with a moderate amount of parental alienation from older women in my children's lives. My partner's mother has made choices that were 'mildly' bad enough that partner let it go for several critical years, thus causing irreparable damage to our family/coparent relationship. She persisted in calling my daughter 'pretty' throughout her early years, which was diametrically opposed to all values I was working to instill in my child. She bought crappy toys in spite of my insistence on having gifts cleared by me first. Disney princess books, etc. I asked, pleaded, insisted, was passive-aggressive, I tried it all.Those things were my right as a mother to make decisions about, depsite the fact that she did not agree with what my child needed. She had her own daughter and now I had mine. That to me, was obvious. It sucks when somebody violates your (in my case, hard-earned) boundaries. (Editing to add, it was in therapy that I finally learned how to make this mess stop).
I think it's HIGHLY possible that the grandma did a bad, bad thing here. If she knows the OP, she'd know not to 'go there'. That said, I'd have let my daughter keep the gift, seethed to my therapist in private, and firmly and politely redefined the boundaries with the grandma. I'd also use it as a clue that my daughter needs/wants things that I don't necessarily yet think she needs, and would be always checking myself for baggage from an abusive childhood RE: gender roles, what little girls should/shouldn't have or do....
I would always try to avoid over-sensationalizing a bra to my child. I don't generally wear one, and hope that it won't occur to my own DD to want one, like, ever. If she does, I'll make sure to get online right away (no shopping in toxic stores with terrible images and additional stuff we don't need) and find some super comfortable ones for her. Hopefully with some kitties on them. Then we'll go back to whatever else we needed to do that day, like cuddling and going to the library.
To return it to grandma might make a bra into a BRA!!!!!!!! with fireworks and fetishes attached.
Edited by AttunedMama - 3/10/11 at 8:39am