Clarification on purchasing site

I entered into a sale agreement to buy middle portion(EW20xNS30 ft, North: Road) of site no. 5. Original land owner (Mr.X) formed layout sites (30x30) in this area. Site no 1 to 3 (each site 30x30) are located towards the east of site no.5. Original owner retained site 4 and 5 (total 60x30) and gifted it to his son (Mr.Y) in August 2007. In this gift deed they mention the site no as 5 and gifted 60x30 = 1800 sg. ft. No mention of site no. 4 in this gift deed. Mr. Y is in possession of this site no.5 from August 2007. In 2018 Mr. Y sold Western portion of site no 5 (20x30) to Mr. A and subsequently sold middle portion (20x30) to Mr. A through two sale deeds and Mr.Y retained the eastern portion(20x30) of site no 5. Mr. A constructed house in western portion and sold it to Mr. B. We have entered a sale agreement to purchase the middle portion vacant land from Mr.A We have found that there is a registered sale deed of site no 4 (15x30). Person Mr.F claiming GPA holder of Mr. X executed the sale deed mentioning site no 4 dimensions as EW15xNS30 ft. This deed was registered in April 2007 (before Mr.X gifted entire site to Mr.Y). Validity of this GPA is unknown but sale deed is registered. In 2009, a permanent injunction petition was filed by Mr.X and Mr.Y against Mr. F. Injunction was requested to restrain Mr. F from claiming ownership of site no.5(60x30). And the judgement decree was awarded in favor of Mr. X and Mr. Y restraining Mr.F from claiming any ownership for site no.5 in 2010. Mr. F didn't go for any appeal. My query is follows: 1). is the sale deed executed by Mr. F claiming GPA for site no:4 valid? This sale deed was not exhibited in the court case. 2) Gift deed by Mr. X to Mr. Y do not mention as site 4 and 5 together but simply mentions as site no. 5 (60x30). Site no. 4 does not come into picture here. But site 4 and 5 together (60x30) was gifted as site no:5. is this valid? 3) Will I face any issues in future if I purchase middle portion of site 5.