If I sign over rights to one child will the military require me sign over my other two?

I want to join the military but I was told I can't go active duty because I have too many dependents. I am married and have three children, 2 with my husband, and my youngest with someone else. My husband and I are legally still married but are not together and haven't been in 5 years, just are waiting for a divorce. My youngest biological father has not been involved with her in over a year and honestly I have know idea where to find him. I am engaged to another man who has been active in my daughters life for the last year and we have plans to marry after my divorce goes through. The recruiter told me that because I am still legally married I could get a dependent wavier but it only goes to 3 dependents and I still have 1 more. My question is, 1) Can I sign over custody of my youngest to my fiance without her biological fathers consent or am I going to have to track him down and go through the courts to do that? And 2) Can I still get the dependency wavier for my other two or by signing over custody of one of my children will they require me to sign the other two over as well? My husband has already made it clear he does not want them full time, and as for the youngest her father is in and out of jail, is unfit, and as I said before I don't know where he is.