I wouldn't do envelopes. I'd do separate accounts. Savings. Bills, Day to day expenses, discretionary. Savings, Bills, have no cards attached. Either autopay, or write checks. Day to day and discretionary have separate cards.

So if she goes out to eat, she uses the discretionary card. If that runs out, and she uses the day-to-day, she'll learn real quick when you're 3 weeks in and tell her "sorry, we can't buy any groceries, you spent all the money going out with your friends. I think there's some peanut butter left in the pantry"

The idea is to let her experience some actual consequences, without it getting you evicted or the lights turned off.