#memory books

It was his series of books meant to teach kids about history that was basically written in a diary format, usually by a female protagonist. Not American Girls. There was usually a picture of the girl, probably an archival photo or illustration, on the front cover and it was "based on true events" but very clearly fictional. I remember reading one about a girl living through the great depression and I think possibly a Chinese migrant in California (not too clear about this). I KNOW I've read this series in elementary and middle school but I can't for the life of me remember the name.

But I can imagine so many other possibilities.

Whether you just started filling one out, are halfway through, or have finished all five years, we'd love to see. Many thanks to @fernanda.motac for sharing this photo.

Boy starts a new school (he moves around a lot I think) and he's used to being like the good kid or whatever. But this time there's a paperwork issue and he's admitted into the school twice, once under his first name and once under his middle name, so everyone thinks he's got a twin. So instead of correcting this issue he just goes with it, attending school as the good kid on some days and attending as like his edgy non-existent twin others. Somehow he manages to explain the fact that no one's ever seen them in the same room. The whole thing comes out during the school talent show or play or whatever and he refused to pick a personality, going with a mix of both and telling everyone to call him J, because no one at this school knows what his actual first name is.

A children's/young adult adventure series about a brother and sister (maybe twins) living in Colorado with their mum, stepdad, and younger sibling. Their mum was a mystery/adventure novelist and their dad had died years ago in a plane crash (he was the pilot). These kids moved to town recently and they solve local mysteries and go on adventures. Had a sort of Hardy boys/Nancy drew/ famous five feel to it

So there's this family who's really into theatre(?) and they have a bunch of kids, and they're all homeschooled, in a kind of set up where the older kids help with the teaching too. The protagonist is the black sheep who is boring and sensible and wants to be an author (or possibly an editor?). The family ends up taking in this delinquent kid who doesn't really get along with our MC, but he slowly starts to soften up after spending time with the younger kids in the family. Through it all, this family is trying to put on a performance of sound of music that's facing a lot of problems.

Anyone else have hose books that you read when you were younger that you really enjoyed but only exist to you now as vague and hazy memories? For me it was the Children of the Lamp series and also this one series about people who could sing to do magic and hey had to fortify a wall with singing? Also most populations lived in isolation because there was a disease that took away their magic and eventually their lives that was spread by touching other people. No idea what this series was called or anything though.