Feeding a large group post partum

I already have enough to worry about feeding my own family of seven. (My husband, myself, my Father-in-law, our 3 teen/pre-teens,and the new baby.) Now my brother-in-law's family has decided that they want to come visit from out of state after the baby is born. They are a family of 4, including two teen (aka ravenous) boys. The adults are also really big eaters. There is a possibility my parents will also be here, meaning I need extremely easy, filling meals that will feed at least 13 people.

When they came to visit for several days during the first trimester when I was feeling kind of miserable, I got away with a couple of big pans of pasta (macaroni and cheese plus one that had ground beef and marinara.) With salad, bread and brownies that stretched to 2 meals, then we had lunchmeat and pizza for the others. I need to think of something different.

Honestly I love having a big family and wouldn't mind at all if it was someone we were close with, but my husband has always had a very strained relationship with his brother. Their kids are rambunctious and a bit difficult for my kids to get along with, and all 4 of them are sort of picky about food. (My sister-in-law is an excellent cook, and also has a good job that makes money for top quality ingredients. I love being a SAHM, but it means we cut corners and buy a lot of cheaper foods.)

If anyone else was posting this, my advice would be to just tell them not to come, but my Father-in-law is 77 years old, and I will not say anything to them that might cause drama and upset him.

Any ideas for what I can feed everyone without killing myself? I imagine they will be here at least 2-3 days. I am going to try to talk them into waiting a couple of months, but as of now it sounds like they are wanting to come pretty soon after the baby is born. :(