Valid of registered sale deed of revenue site

Hello sir, i bought one revenue site measuring 30x40 feets registered in 1985 from land owner at kunigal taluk ,tumkur, A land owner was having 1 acre of agriculture land. Out of this land owner converted( Not Dc conversion just revenue sites) 50% of land as sites ( 10 sites was made measuring 30x40 feets) and for all these sites land owner himself gave sites numbers (khanasmari numbers) and kept 50% of remaining land as it is with him. Registration was done at sub register office kunigal taluk. When registration was done, in sale deed survey number was not mentioned instead of survey number khanasmari number(this khanasmari number was given to site by owner himself.) was mentioned along with boundaries of east,west north and south. Recently land owner expired in 2011 and now his son is telling that all the 10 sites what his father was made in 1985 was illegal since RTC (Phani) of entire 1 acre is still in the name of his father so now he will be the absolute owner for this 1 acre land and he is forcing me to vacate the land. For this purchased site im getting Katha Extract at Grama Panchayat office and im paying property tax from the 1985 to till date . but the thing is my name is not reflecting in RTC. kindly give the suggestion whether my sale deed is valid or not. Regards, G. Shivakumar