General power of attorney

My father and his brother get a property through a sale deed from his father of 1 hectare and 35 guntas Later the Brothers were divided into pieces and my father got 39 guntas of land In the 39 Guntas my father made development of 10 guntas and remaining 29 Guntas doing agricultural activities My father had three daughters and one son Later My father decided to convert the remaining land. Due to some reasons we give land to convert one devloper and we took adavnce as 1 lakh in 290000. And the father mother and the son exicuted the sale agreement deed. After 8 months the devloper requested as to give GPA for fast conversion and he shown as we recvied the GPA deed (here the whole family including the daughters were as principal's as exicuted GPA )and the devloper is an agent Without the concent or infromation to the pricipal the devloper or agent executied a sale agreement to sum 3rd for 4 lakhs After 4years still he dint done any type of conversion. Due to personal issues we infromed him that we planing to sell our land of 26 guntas in 29guntas and we will pay you the 2lakh 9೦000 rupees The devloper agreed that he said that iam ready to take orbuy the land of 26 guntas in 29 guntas for sum amount We made a 11e skech and the land lord and the devloper were both are agreeed in that 11e skech Without paying money and wid out infroming the principal the agent or devloper cancelled the sale agreement deed which is made wid 3rd person for 4lakh And the agent exicuted the principal's property to himself by showing consideration of 2lakh 90000 And he also payed stamp duty for ten lakhs rupees When we get to know that he made these things we made objections infornt of thashildar that the devloper mis used the GPA but the thasildar dismissed the objection and made a revenue entry on the devloper name The three daughters filed a civil suit for partion and maded party as the devloper,father mother and the son The father appealed to assistant commissioner court and said the facts and shown the 11e skech in which the agent accepted that he will buy the property of 26guntas in 29 guntas but he is not And also we given the supreme court judgements of suraj lamps and state of hariyana Shivakumar v/s union of india In which the cleary said about the GPA The honble AC convinced and he appreciated it. Now the devloper went to DC court and the dc gave a stay order to AC orders MY QUESTIONS ARE 1. still i dint present or appeared in DC court Can i directly go to high court is der any option let me know that how can i go through (the way ) 2. Can we get success aganist the devloper 3.the sale deed made by agent to himself is valid?? 4.what happens the civil suit which is filed by the daughters Or any other suggestions to the case