Breeding her with her son is probably not the best idea. Ever heard of inbreeding? That's what you would be doing, and it isn't a great idea. Find a male from a different source, maybe get it shipped in.
It's ok to go back to the son. You don't want to keep doing it generation after generation but once back wouln't create two headed fish with week genes. You would be better of with an unrelated fish but if your going to use the fry as feeders or raise a couple to see what they turn out like go ahead. It's ok.
Breeding her with her son is probably not the best idea. Ever heard of inbreeding? That's what you would be doing, and it isn't a great idea. Find a male from a different source, maybe get it shipped in.
This is true. Hybrids have a much greater gene diversity than a regular species of fish so you'd need to do some serious inbreeding to get anything too bad out of it.
I would like to mention that inbreeding is a regular part of fish breeding. Look at any number of different fish, snakes, frogs, dogs, horses, rodents, insects (Insects are pretty popular in asia), even plants. They do it when they are looking for a specific trait. For example the albino gene is recessive, so when an albino shows up they will breed the child back onto the parent to solidify the gene the process can/will be repeated for "better" results.