Extra people on the lease

[Gabe N.]

I just had some new tenants move in (a family of 3). When i met them in order to give them the keys I found out that the spouse was 8+ months pregnant. A few days later I found out that her mom will be staying with them for a few weeks in order to help out with the new baby. In my lease agreements it states that no one can stay longer than 1 week without landlords permission.

Even though they never asked me for permission, I honestly dont have any problems if the mother in law lives with them for a few months to help with the baby. However I am curious apart from financial responsibility is there any other reason why everyone who lives in the house needs to be on the lease?

Is it in my best interest to add the newborn to the lease as soon as possible?

What is the best way to handle this type of situation?