Can Family Court modify the stipulation of settlement?

All incorrect information is on it and made it very unfair to my husband. It states that he is making $61,000 annually but in 2005(was still with her) made $15,000 and 2006(filed for divorce) made $18,000. His lawyer later told my husband to sign the stipulation and said he can terminate some of it and even modify it later after he signs it otherwise he have to pay more money now to fight it and he was poor at the time and he signed it and believing that he is able to change it later on. My husband went back to the lawyer after he signed it then the lawyer didnt want to take the case anymore. What a bad job this lawyer did! It says he has to pay $1000 in child support and $600 a month alimony. This is very unfair. Stipulation says that that it shall survive, and not be merged into, any judgement, decree or order, and the parties shall remain bound to the performance of the stipulation It shall not be amended modified discharged or terminated etc ..