My daughter and her roommate found out that the new tenants were paying only $1750 for a way better unit (larger, fireplace, wood floors, etc.).

Hi @Gio Franco We have a lot of owners in my market of Chicago that buy a condo and get a roommate(s).

I had a roommate like this for my first house hack and she was great at first, but I didn't stay strict on certain rules and things got stretched out more than they should have haha. 

I currently use Innago, which helps me use and distribute applications, lease agreements and roommate policies, collect rent, security deposits, and has an accounting system.

We would also to get 1 or 2 other roommates in the house.Has anyone ever had this type of arrangement?

It sounds like your husband is open to investing or even house hacking, just not with roommates.

When we did our last walkthrough, I suspected they have a roommate. 

I know people living in DC with, master's degrees from prestigious colleges and professional jobs , who rent a house shared by other professional roommates, because they can't afford to rent on their own.

But house hacking a 2-4 unit without shared roommates is pretty straightforward.

Marketing it as a three bedroom brings in a family with two kids or group of three roommates, and it's way too small for 3-4 people.