sure you can. you can do whatever you want to do right after the tnb meter.

what you cannot do is with modification within meter or before meter.

see those two wires out of your meter? (main and neutral) yes, that is your territory.

sure why not.

i dont face such setup before but it can be done actually.

normally if you have big complex (shopping complex for example), have lots of tenants and you are taking bulk supply from tnb then go ahead and do it. but for residential i dont think that is really necessary..

whats the problem you are facing actually? overcharging in electrical bill?

i am not so sure, about cost. but it is more practical for a larger premis.

but for only three room and each have its own meter? well, you are the landlord, its your call.