Property sold

Dear sir My grandfather sold one property in 2006 which was mortgaged to him for a sum of 1.5 lc INR in 1998 under a signed agreement where the other party promised to return the money with interest within 2 years which never happened. he was served notice in 2001 to return the money which he did not do and even did not appear in the court upon multiple attempts being made to serve him the summon. eventually, an exparte judgement was passed in favour of my grandfather and he sold the property. Since 2006 a constant battle has been going on between both parties. The other party is asking to return the land and he will repay the amount. To date that piece of land (then agricultural) has been sold 5 times and the current owner has built a house over it. My Grandfather and Grandmother died in 2011 & 2019. Since then the summon has been coming in my father's and uncle's name. I have couple of pointed questions which are as below; 1) land sold by my grandfather, how much my father is liable? 2) the land was sold for 1.75 lc to recover the money and now the current value of the land is around 1 Cr, so how does the court see this? 3) a hearing on the same matter is pending in the high court (in April 2025) and the other party has filed another case for the same in the lower session court. Is this case maintainable? 4) Just in case if court passes judgment against us, then what could be the damages we will have to incur and how much my father be liable to pay (my father has 2 brothers and 1 sister) 5) the lower court passed the judgement in our favour in 2003 and after that, only my grandfather sold the property, so what he did was legally correct or incorrect as the session court on one instance dismissed the lower court judgement stating that the previous judge did not account for many things.