The other is a triplex, all units are 2 bed 1 bath. 

He took a 401(k) loan to fund the down payment on a four-unit building in a rapidly appreciating neighborhood.

If you are still willing to stay in the same unit as your brother you can get a 2-4 unit building, rent out the other units and still rent a bedroom within your unit to your brother for extra income.

Will you please break that down for clarity at a newby level?

Financing can also vary depending on whether it’s 2-4 units or 5+ units so keep that in mind as well.Having a strong team and lender familiar with multifamily deals is crucial.

I was going through the rent control laws ( I know, should have done that before purchasing the property ), and a section stands out. https://ecode360.com/30526708#42037155Based on what I can read, the rent control chapter doesn't apply to: Dwellings of three and four units, at least one of which is occupied by one or more of the owners thereof.My understanding is that rent control doesn't apply to owner-occupied multi-units. 

Best,WilliamThis introduction highlights your enthusiasm, transparency about your experience level, and desire to connect with others while establishing your goals.

Quote from @Tim Horning: Hi Carl, I am going thru the exact same issue with my first rental; a large 3 unit house.

He ultimately refi’d into a loan that felt hefty at first, but it freed him up to add another unit in the building.

I have bought a couple of units and now working on my own development.