Agriculture Land Question

Dear Advocates Fraternity, Hope everyone is doing well and staying safe during corona time. I've a question on 2 Agriculture land issues. Queston1: My father bought (self acquired) 2 acres of Agriculture land in 1975 and put it on my Mother's name. My sister got married in 1988 and we all decided to give this land to my sister. My father expired in 2005. Since these 2 acres is on my Mother's name, we think its not a problem. We wanted to transfer this land to my sister's name without Gift deed/ registration and she doesn't want to sell that property right now but they want to have some document so they can sell later. If they want to sell when my mother is alive then my mother will sign on the sale deed document. Option1: Is it fine if my Mother writes an un-registered WILL and we all siblings sign (like witness sign or general sign) on that Un-registered WILL so later, we can't say the WILL is fabricated as we are also the beneficiaries of that property. Option 2: Shall we go ahead with Registered WILL given by Mother to My sister ? Option 3: Shall we go for Sale Deed/ registration only ? Question2: Second question to the continuation of the above Question 1: My father bought (self acquired) 1 acre of agriculture land in 1983. He sold the same to my sister in 1996 but again, no registration happened or not written any WILL or paper. My father expired in 2005. How to transfer this property to my sister's name. My sister doesn't want to sell that property right now but she is looking for a formal right. At the same time, we would like to avoid, Sale Deed/ Registration right now. Option1: Is it fine if my Mother writes an un-registered WILL and and taking NOC from all the siblings of my sister is enough ? Option 2: Shall we go for Sale Deed/ registration only ? Best Regards, Srinivas