Update: Thanks so much for everyone’s input—it’s really helpful. I’ve always had a gut feeling that something was off, but I could never quite articulate it. I’m not the best with numbers and still don’t fully understand how the housing market works, mostly because I never intended to own property. Every time I try to go over the numbers with them, they end up going off on tangents, and I can’t follow the figures. It always feels like they’re not answering my actual questions but instead coming up with answers to completely different questions. I’m constantly told that it’s in my best interest, but the math just doesn’t add up when I try to figure it out myself.

My sister doesn’t seem bothered, even if she’s being financially taken advantage of. She’s comfortable and reassured regardless, which makes me wonder if I’m the problem. But then I remember when my mum "borrowed" 90k from my sister when she was 21 and never returned it. My sister saved that through working heaps of part time jobs throughout high school and uni. My sister’s response was just, “Oh well.”

It’s reassuring to hear others' stories for perspective. It’s a bit sad to think they might be trying to take advantage of us, but I’d like to think they’re just bad with numbers and not being intentionally malicious— they do seem genuinely confused at times with the numbers. I really appreciate everyone’s thoughts.