If you decide to keep just these foster children, the foster home approval process is easy when it's "child specific". I went through it that way for my step niece, which years later became my adopted daughter. What I thought was one of the most ridiculous things I had to do, was clear a shelf in the fridge specifically for her food.
After talking with a couple other foster parents and kids, I learned that in some of the homes there are in-house kids (the parent's own children) vs the foster kids. The foster parents cook, and feed the foster kids differently from their own kids. The foster kids get food stamps (EBT card), and it's not overly generous. Instead of making a meal sufficient for the entire bunch, those foster parents only fed the foster kids with whatever the food stamps could provide. I didn't do that.
I made meals, and we all ate the same. I bought the bigger bags of apples, grapes, a couple bunches of bananas, etc., which everyone snacked on as they wanted, and I replaced as needed. I bought family packs of meats, big bags of potatoes, big bags of carrots, etc. When they'd announce they were coming for an inspection, which wasn't often (not just the normal case worker visits) I'd toss a few apples, put a clump of hamburger meat, or a pork chop, or whatever, into a baggie, grab a few bags of frozen vegetables, toss in a few potatoes, then put it on the foster child shelf in the fridge. My fridge and freezer were always packed full, and they knew I fed everyone the same, but rules are rules, right?