Yes, no matter what Thief will find away. Because he is Thief.

Speaking as someone that has taken several Business Law courses at my University I'd like to think I'm somewhat qualified to answer this question.

It would entirely depend on the language of the contract, of course, but under most circumstances if one party of the contract dies that particular portion of the contract immediatly becomes void. It would really depend on if each character is considered to be a differnent party in the terms of the contract(Thief, RM, BM, Fighter) or if there are two parties(Thief, and then the rest work for him).
If there are only two parties, BM's death would significantly change the terms of the contract to the extent that it'd have to be restructered or voided. If each party is seperate, it's likely the contract would remain intact, but the portion regarding BM's obligations would be nulled. When he revives, BM would no longer be obligated to Thief to do whatever the contract reads. Unless in the contract it specifically mentions what should occur if a person in the contract is considered to be legally dead and then returns to life. Which I'm guessing Thief is smart enough to do.

I think there are five parties-Fighter, Thief, BM, RM, and the party as a whole, because Thief refers to himself as the party of the fifth part

Knowing Thief, master of obfuscation and lies, he included in the contract a clause stating that the contract retains all...stuff... even in case of death, upon which time Thief gains control of their souls.

either that or theif, just had super super super super x infinty FINE PRINT

yeah, he's probably written in fine print on the bottom:

In-case of death and ressurection or rebirth, the contract remains valid. :D

Maybe BM will destroy it with a Fire Spell

Now that i think about it since this is Final Fantasy Thief would have remembered the death clause and that people can be revived. Thus he would prevent such a loop-hole from forming

I think this is a question brian would have to answer, cuz only he knows the teenie weenie details of the contract.

Or just maybe he makes bits up as and when they are convenient :rolleyes: .