Another option might be to squeeze out a filter sponge into the tank... Fry also eat lots of microscopic organisms that can survive on the mulm found in a filter sponge.
There are always options. I guess the simplest solution for you might be to just provide a great deal of fry cover to the tank that they were born in and allow the fry to fend for themselves. If they survive, they survive. If not, then you won't have to worry about overcrowding in your tank. That too may sound harsh, but it would eliminate a bit of your dilemma. Just don't look around for eggs, etc and chances are you may never see any until they are big enough to come out of their hiding places.
I've had two batches of cory eggs laid recently, but since I was going to be away from home so much this summer (like now for example) I just left them. A few hours later, the eggs were gone. This isn't a case of you "feeding live" fish to the tank. This would be a case of you not intervening in the life cycle of the tank. Long story short, fish fry are a standard food of almost every fish. If they can fit it into their mouth, they are going to eat them. By not stepping in, you are allowing your micro-ecosystem to play out fully.
Of course, if you are looking to breed your fish, then I think that you have to consider the costs of such an operation, and one of those costs might just be getting over your feelings about not feedings BBS to them. If you can't do that, then I would suggest you don't try to breed, and just let "nature" take its course in your tank without you rescuing the fry.