So what do you do about one of the rooms not having its own individual restroom?

Don't get your shorts in a bunch if you get caught doing wrong on purpose.Regulations make good reading in the restroom at my house.

Laundry room, restrooms and showers are basically it.

Would the layout of the house allow for the addition of a third restroom?

I thought it was one of our kids getting up to use the restroom; so, I got up to help them. 

Then, there's people that don't want to do anything for the homeless, but complain they are defecating everywhere when there's no facilities for them to use restrooms, and for good reason, they use them for doing drugs, having sex, and trash them.

I noticed one other problem overweekend , a sweaty vent, just one vent though in the restroom.

A total living area above the garage apartment, with its own AC&heating unit, complete with restroom and shower. 6. 

One of their biggest issues was that they were not on town water and sewer and were going to have to dig a well to service the showering and restroom facilities as well as build s septic system to handle the proposed traffic.

I got a quote for for both the hallway restroom and the master shower walls, it came out close to $1,200.