This sounds like your award booking service advised you to do the transfer. To me, this would make it partly their responsibility in that they should have checked the rules before telling you to do the transfer, especially if you could have transferred to husband's FF account and used "his" miles for at least some of the tickets. However, it also sounds like your award booking service might not be real good, so I'd be a bit reluctant to trust them to figure out how to solve the problem.

I'd start by finding and carefully reading exactly what the rules are for AmEx to SQ transfers. If you can transfer within the family, give SQ evidence of your relation and the problem should be solved. Otherwise, check the rules on primary versus secondary cardholders, etc.