Is the mutual divorce agreement unfair to my sister's rights?

The agreement for mutual divorce prepared by the lawyer is in favor of her husband and does not favor my sister in any way. The agreement states that no inherited property will be demanded in the future, no maintenance or alimony will be given, and child custody will be borne by my sister as she is capable. My sister is a teacher with no pension or medical facilities, whereas her husband is an engineer who earns very well and has all the benefits provided by his company. Our parents have been taking care of her child since he was one year old, and now the child is 11 years old. Not a single responsibility has been taken by her husband towards her or the child. She also tried to live with her husband and his family as per the family court's suggestion, but they ill-treated her mentally and physically, and created situations that were not favorable to her. She has been taking care of the child as a single parent with no support.