Family based lending

[Theodor Kim]

Hey all, so kind of a strange question, but:

What’s the best contract template to use to have a family member “trust loan” me money with an unknown return and returning their principle (and profits) in a set amount of years?

Context: I’ve been teaching my siblings how to do their finances and one of them was able to save a decent lump sum of cash. She knows near nothing about real estate and wants me to put it to work. She trusts me to throw it in a deal and eventually wants her principle back (I intend on giving her all the cashflow/profit to show her the power of real estate). She also trusts me without a contract but I also want her to sign one to teach her safe practice (and to have something that is written).

It isn't a significant enough of an amount of funds and not a long enough time to start a JV Partnership with a bank account opened so I rather do something with less cost and strings more like a Note or Advisor/Manager which I'll run in my businesses account. I know it's kinda legal stuff but if anyone has insight, I'd love to hear it!