Answer:
Yes
Step-by-step explanation:
Yes, in such a situation the promise must be written and signed by both parties in order for it to be enforceable. This is mainly due to the fact that the promise is being made for circumstances regarding a third individual which therefore makes this a Collateral promise. Collateral Promises must be written and signed in order for it to take effect and protect all parties involved from backing out of the contract, which doing so would be considered fraud.