I wear Rago brand, long-line bras. They have lace cups with nylon linings. I had always read that forms required adhesives or a pocket bra to look right, but as long as the cup is sized correctly to fit the forms, my experience is any bra will do. Silicone forms can be a little delicate and I have read that underwires could puncture them. My breast forms are called Pals; I bought them from Glamour Boutique. They are very realistic, yet they will not leak like a conventional silicone form. In fact, they are claimed to be self-healing and they can actually be trimmed for a custom fit. I really like them a lot.
Hugs,
Sally