Asking about rules for re-admitted students from R16 to R18

Actually, My original batch is R16 batch but i was detained in 3rd year then I got promotion the 3rd year in R18 batch but already my 1st and 2nd year are in R16 and other 3rd and 4th years are in R18. So now I have passed all my subjects for R18 and now I have only One backlog that is Mathematics 2 which is included in R16 batch . Here I would like to ask you that as my backlog (M2) is in R16, Can it be exempted as per rules and regulations of R16 but in R18 there is no chance for subject exemptions. And lastly I’m asking that to which regulations (R16 or R18) should I follow the rules for grace marks and subject exemption…?