You can merge two LIVE Gold accounts into one Family Pack easily, but is there a way to dissolve the family and get those months back for an individual/single/solitary account (even if for just one)? The Xbox forums are unhelpful and generally suggest waiting for the Family Pack's time to run out before reupping (but that's the subscription time/credit I wanted to save).
To cancel an xbox live subscription before it runs out you need to contact xbox support. Give them a call and tell them that you want to separate them and change them to gold accounts. You probably won't get enough credit to keep both accounts on separate gold live but you should at least get one on for that time and some credits. Maybe they can shorten the time and get both accounts gold live. Worst case they would just cancel your family membership and give you credit for the remaining month. Then you just have to signup for gold on each account again.