They give their mother money of varying amounts, and she saves some of it; should it be returned to them in the same proportions as they gave it after she dies?
Question

We are three brothers. The oldest of us works as a petroleum engineer, the second son works as an Arabic language teacher in a private language school, and I work in customer service. Every month, we give our mother some money, each according to his financial ability. So, for example, the engineer gives 1000 pounds, the teacher gives 600 pounds, and I give 300 pounds, so the ratio is 10:6:3. Our mother saves some of this money. In the event of our mother’s death, should this money be shared out among us equally or according to the amount that each of us gave? May Allah reward you with good.
Praise be to Allah.This money that is given to your mother by way of showing kindness and upholding ties of kinship – as appears to be the case and as is usually the case – is her property, and if she leaves anything of it behind when she dies, it is to be included with her estate and divided among her heirs without taking into consideration what they gave to her. So her sons should receive equal shares of it.
But if what was given to her was by way of a loan, it also belongs to her so long as she is alive, then if she dies without having paid off the loan, it should be taken from her estate and returned to the creditors, according to what is owed to each of them, before the estate is divided, because Allah, may He be exalted, says regarding inheritance (interpretation of the meaning): {after any bequest he [may have] made or debt} [an-Nisa’ 4:11].
And Allah knows best.