How to buy multi-unit property with partner

[Carl Evanko]

Hello everyone, My name is Carl Evanko and I am new to the site and new to investing. I am looking to possibly start my investing journey with a family member (Brother or Sister in Law) as a partner. We are interested in buying a multi-unit property as our first investment. Ideally, the property would be a 3-4 unit building. I am able to provide the necessary down payment and they would (Hopefully) be eligible for an FHA loan. I am unsure of how to structure the partnership that's fair for both of us. Since they would be living in one of the units, should they be paying an additional 25-33% for occupying that unit? Since they would be living in one of the units, they would be willing to manage the property for at least that time frame. I would also like to factor in that as part of the calculation. The other thing I am unsure of is, would I try to be on the mortgage (Is that allowed) or if a true venture partnership is necessary.

For those that are curious as to why I don't just try to do this on my own, I am married with 2 kids. I run a small kitchen remodeling/custom cabinet business from my single-family residence which is ideal for my business deliveries. I also love the idea of getting my brother or sister in law involved to help them out in the process.  

How would you go about structuring the partnership and what factors should I be thinking about that maybe I am not. Thanks for any assistance you can provide.