i heard back from my cousin. turns out the dress shop wouldn't let them cancel the dresses. So we had two options. We could either go pay for the rest of the dress and keep it (to wear or resale) or the dress store would keep the dresses and deposit and just try to sell them themselves in the store and my cousin would pay us back our deposit.
She sent out a msg to all the bm's. They're paying us back one by one as they can. Of course, people started asking that they be paid back first b/c of this or that. Her mom sent me a msg the next day to ask how much my deposit was and said she'd pay me back as soon as she could. So her mom is winding up paying us all back. I feel bad, but I'm happy to get the money. SIL just got engaged last weekend and I can really use that money to buy the new dress for her wedding!
I'm glad I spoke up. All the other bms wanted their money back too apparently, but were just too scared to say anything.
Re: update on the bm dress