Yes, once the floor is buried, the room becomes unusable and maintenance impossible. So, although it seems reasonable, sharing the closets is only increasing the clutter while costing you the use of an entire room.
Reclaim your space and take advantage of her large room by placing an armoire with hanging space and two chests of drawers in her bedroom. Tall chests are space-efficient, but each of you needs one low wide bureau with a mirror on top for hair, makeup, and jewelry. Place a basket-style laundry hamper in your daughter’s room, so she can manage her own laundry. Most important, both of you should weed your clothing until the remainder fits comfortably into your bedroom storage.
And for you, mom, that still means one closet. Use that second closet as a utility closet for the vacuum and select cleaning supplies, or storage for photos and memorabilia. Let it work for you as a tool to de-clutter the apartment, instead of being a trap that tricks you into retaining more clothing. This can all be managed without sacrificing the floor.