Try it out first test out whether or not you two are a good fit before building a massive portfolio together.Create an operating agreement for your LLC, and create a partnership agreement, defining roles and expectations.

However, just get in, see where you fit, and build over a decent pace where down the line you will be doing great.

Immigrants help build homes, work in construction, and fill critical labor shortages.

I have helped hundreds of investors execute 1031 exchanges and build diversified portfolios across various excellent markets, all while using just one property management service.

Also unfortunately, we haven't held anything yet to build a portfolio.

I come from Europe too, and I know it can be overwhelming when you look at the real estate market in a new country and with completely different building technics ( sticks instead of bricks), but is not as bad when you have the right team in place. 

Bonus Tip: If this quadruplex is out of state, I’d highly recommend building a reliable local team (cleaners, handymen, etc.) and maybe consider hiring a co-host or VA to help with day-to-day tasks, especially if you scale up. 

What is status of capex on the building?

@Aaron Washington wind insurance is a must unless you have master insurance in place that covers your building.

I recently closed on a commercial condo unit (for retail), which is one unit in a building that also has 7 apartments.