Is it permissible for a man to take from the allowance of the disabled (90 dinars) and add it to his personal salary to spend on their other siblings?

What the "Elderly Fund" has allocated to the two disabled children is considered their property, and the father is not permitted to spend any part of the amount for anything other than their benefit, unless he is compelled to spend on himself or on someone whose maintenance is obligatory upon him. In that case, he may take from their money what removes that necessity.