@ Poster
I'm Igbo O! but that doesn't mean i should support what is not right.
I feel you. It's not like the guy is a millionaire - he's trying to start up his own life with the little resources he has.
These so called sisters have jobs O! It's not like they are broke O! they are just being wicked. they want to save their money and
keep drying their brother up.
I feel you should explain to your guy that if he continues like this, he would not have any savings to put up his future.
I'm not saying he should not assist them when the need arises,
but putting people that have jobs on monthly allowance to his own detriment, abeg that is too much.

He has to make a decision on which is more important to him -
supplying his siters greedy needs or
building a future for himself. I once had a guy like that. this one was not even his sisters that were demanding; it waz one grandmother's step son's daughter somewhere in the village, or one uncle he has never seen before but hears his name

and he was always complaining that he was broke. He cud not plan his life (because any little money he saves they are already there with their demands).

Me, I did not even tell him anything but I just resolved in my mind that I can't marry him. one day he told that me that one of his ex's was always complaining about his extravagant life style and he was begining to see reasons with her.
So talk to him about it, don't nag him O! Explain the consequences of his actions to his future. If he still doesn't see anything in it - and you cannot stand it any longer, then you could leave the relationship. But someday he would appreciate the fact that someone once cared enough to advice him - and he would see what he has done to himself.
Hope it won't be too late by then!
Good Luck!