Hi, I'm sorry to hear what you are going through.
Gardenofedens gave some excellent advice though and I hope you and your family think carefully about the decision.
I have worked with several dog rescues since my late teens and foster dogs for small UK rescues. I don't know what country you are in, but in the UK the harsh reality is that if your dog has a history of biting, it will not find a new home, it will be put to sleep. There are simply too many dogs in rescue, dogs with excellent temperaments, with pedigrees, cute puppies and desirable breeds for a dog known to show aggression towards humans to be rehomed easily.
I don't mean to upset you - but a lot of people have the idea that there are a million and one happy families in country homes or farms with acres of land that they can send their unwanted or untrained or inconvenient dog to via a rescue. I do realise that especially with a child this is a very difficult situation for you to be in but on behalf of your dog I would ask you to at least think about contacting a qualified behaviourist to try to resolve the problem and give it a chance. In the meantime there are very likely common sense measures you can take to keep the 'problem' dog separate from the others, using child gates, crating during meal times or other stressful periods, or just keeping doors shut between them.
I hope I haven't offended you and it is not my intention to - I do understand how difficult this situation is. But every day I see and hear about lovely dogs being destroyed because there is simply no room for them in rescue or foster care, and they can't speak up for themselves.