House Hacking with Friends and Family

[Immanuel Pierre]

I recently bought my second house hack in October 2022. My roommates/tenants are my mother (recently divorced), my sister (over night nurse, who spends most days at her boyfriends), and a coworker I have known for years. Before buying the house everyone knew the terms and what the living situation was going to be. My friend just recently came back from Colombia (within a week of this post) and I did not charge him while he was away. Everyone knew this. Upon his return my mother and sister have both asks if rent would be the same amount because there was an extra person paying now. I thought this was a little odd to ask and was not sure how to go about it, so I told them that it was the same and I did not really expect to change it. Neither of their quality of life has changed, I volunteered to give up space to accommodate the additional person. So my two questions are, Was it a reasonable question for them to ask does the rent change when they knew he was eventually moving in? Should I lower the rent amount since there is an extra person now? 

Rent is $1100 each and the mortgage plus HOA comes out to $3300. I have been covering utilities.