Anyway, I did the transfer though MYSIKAP already and found out that my brother doesn't need to renew his roadtax until the current roadtax expires (in March).
You can also get a refund for the roadtax if you cancel the roadtax before you do the transfer online (but I skipped this step).

Another thing I found out is that instead of the grant, they now need the owner's IC for roadtax renewal at post offices.

The only thing my brother need to do now is to walk into JPJ with the grant and get the new VOC...

I hope this info helps those who are doing their transfer through MYSIKAP like me.

P.s: thanks to those who replied to my questions. Really appreciate it.