A.R.
I, too, think what you are doing is wonderful!! and I have a slightly different take. I'd suggest getting gift cards, if possible one for each child AND mom and dad to for example a Super Walmart or Super Target. That way, not only will they each receive something they want/need, but they could have the self-esteem/satisfaction of buying for someone else in their family, if they choose. That is, they could use the card to buy for themselves, or choose to each buy for another in their family, and mom and dad would know the feeling of "having enough" to buy a gift.
Again, whatever you choose to do it is wonderful for you to embrace them and their needs!