GPA Cum sales deed reg., Our impoveable land some person created unregistred will in white paper, his Grand father given

thank,s for your valued reply in this subject. Actual we have registrar the propritey in 1995 50 cent of veccant land in that 35 cents one survey and 15 cents another survey. The 35 cents proprity belongs some SC/St person sold at 1923. Present two gand sons of first sold person they them self created unregister will in his father name, they say that father was dead & we r the L.R. of the proprity and they sold to some reddys under GPA Cum sales. who R the GPA Excutor the proprity one he dead last 1 year back. My ? is wheater gpa cum sales deed it will valuable for the them or not, if not valuable what is to be take next action on them.
Awaiting for your reply on this we highly appreacte you sir. Thanking you.