We are doing modern times right now. We thorougly enjoy all the books!!! We are doing family, 1st-3rd and 4th – 6th books. The kids and I have learned so much and the books have been so good even as they cover sensitive topics with wars and such.
My oldest is in 5th and she has no problem reading the books and narrating to me. You know your 7th grader besr but they might not challenge her enough, but they could also be a perfect fit too.
Also if all 3 read the same book will you read aloud or will they have to shuffle the book between all 3? Right now my oldest reads those to herself and I read the family and 1st -3rd aloud to everyone.
Since younger siblings will be using the books, I see buying the books as an investment. This year as we cycle back to Ancients I only have to purchase a few books for the next level up, so far it has worked out.