confusion abt dia & his bro uday

In thursday episode they showed dia's younger bro uday in mayanks class they r elder 2 them then how com they were in there class & if they were giving proxy for someone 😕 😆 😉 that 2 in devdhar's class wht a guts this guy has 😆 😆 because it can not happen ki dia fail hokar sammy ke sath ho gayi leaving his bro 2 study in higher grade. pls commment on this as i already said i m totally confused 😳.

thanxs in advance😊