Anyone know what series this is?

It's a series aimed at younger readers about a girl who grew up with a close tie to indians. The person she'd been living with, her dad(?), died, and she had to go live in a more populated area with her aunt and uncle who were really rich. I think she was sent off to an all girl's boarding school that occasionally had joint events with an all boy's school. She became close to a rich boy from that other school, and her childhood friend was jealous (he'd promised to get her dad's cabin back someday and marry her). Think she had a tendency of getting in trouble and solving mysteries, but I don't really remember much else. >_< Does that ring a bell for anyone? I tried looking through my library checkout history, but I don't think it records as far back as when I checked out those books. Oh. Also, her aunt and uncle had a child of their own later on in the series that was sick and always crying, and the girl was jealous at no longer being the only child.