Countdown to Stepkids: 10 Days

Ten days left until my stepkids are here. I am still trying to figure out how to feed my newly turned vegan teenaged stepdaughter, while feeding five other non-vegan children, without busting our budget. The last time they were here, we busted the budget (we didn't just bust it, we smashed it to smithereens) and she wasn't even vegan last time (yes, it was just in March...things change quickly I guess). We can't do that again (go beyond budget). We couldn't afford it then and we certainly can't afford to do it now. I have to figure out how to buy a week's worth of groceries for six kids and two adults, one of the kids vegan, on a tight budget. This is going to be interesting.

Does anybody know how to feed a vegan teen affordably?