Ancestral Family Partition

My maternal great grandparents had 5 sons. Though the partition had happened back in the 80s, there was one piece of land that was still in the name of my great-grandmother. My grandfather’s brothers excluded us from the property and sold off that land through an agreement. My mother filed a case against the same, and it’s still active in the court. A few months back, both the parties agreed to settle the case outside the court through a partition. My maternal grandparents have 4 children (2 sons and 2 daughters). Out of this, my eldest aunt and uncle didn’t want to come and sign the partition deed for reasons unknown. Since they weren’t ready to sign the portion, my mother and my uncle signed the partition and the deed got registered. Now the share which was supposed to come to my grandfather is in the name of my mother and my uncle. When informed about this partition, my eldest aunt wants to file a case to cancel the partition and get a new partition made. Here are my questions: 1. Can she cancel the partition? If yes, what would the procedure for that be? 2. If we want to spilt the share which is in the name of 2 siblings with the other 2 siblings, what is the procedure for that? 3. The partition deed which has been registered, is it legal considering that it excludes 2 parties who are very much alive but didn’t want to sign the partition deed.