Um.... that's a little strange.
I can see things being a little large because kids grow fast, but that many sizes? ESPECIALLY shoes?!
IMO I wouldn't knit for them unless she let me measure them and even then I'd have to think long and hard about it. If you are willing to go to all that work she needs to understand that knitted clothing is not like store bought. Sizes vary by type of yarn and needle size, too. Even if you were going to make them larger you don't want them to look like they are wearing their parent's clothing so measuring is important. Good luck!