I hate to tell you this @CynthiaRothrock but these parents are mugging you off. Been there done that, and would never do it again. We (me and DH,) just got used, and got no thanks - from the parents, OR the children. Ever.
We looked after a multitude of neighbourhood children for parents who weren't arsed to do it themselves, and were often at the pub, or out with their mates, or at work, or they were paying attention to younger siblings, and couldn't be arsed with the older/teen child. And as I say, the parents never thanked us for it.
And in some cases, after a while (around 9 to 15 months,) the particular friend of DD's would fall out with her, and they'd stop coming around, and we never, ever got thanks from her either (for all the months/whole year sometimes or more,) that we had looked after her, fed her, and taken her out on day trips, and out for meals with us.
Sometimes it was not that the parent was not arsed with the child, it was that the child didn't like the rules and regulations in the household, or they wanted to get away from a sibling. They'd say 'I like it here, it's so much calmer and quieter, I can do what I like here blah blah blah......' Then they'd stay til 8pm or 9pm sometimes, and say they couldn't go home as there was no-one there, and they didn't have a key. (If we took them home which was quite often, sometimes there wasn't someone there, and sometimes there was.)
You can be the Chief Carer, Nanny, and Nurse for the neighbourhood children if your like, but as I say, no-one will thank you for it. Parents WILL mug you off. Plus, even if a child has got parents who CBA with them, why is it the responsibility of the parents of their friends to look after them/feed them/sort their problems etc, when they have their OWN children to look after, a job, a home to look after, other family/elderly and ailing parents etc...?
I may be projecting a bit as DH and I were used and mugged off by some many parents for about a decade, (just didn't see it/realise it for ages,) but I have to say, the parents of these children are virtually all mugging you off. You may be OK with that, and if you are then good luck to you. I would never be doing it again though.