New Tenants are Asking to have a Family Member and 2 kids move in

[Cameron Lieverse]

Hi everyone,

I have just signed a new lease with tenants for a 3 bedroom main floor in a duplex. The tenants have 3 kids as well as a dog and cat. Due to a family emergency they have asked if a sister-in-law can move in with her 2 kids. This means there would be a total of 5 kids, 2 adults, and 2 pets in a 1000 square foot home. 

Undoubtedly there will be some repairs to be made with this many tenants under one roof. I have told the tenants that there will be a rent increase if their sister-in-law, but I am unsure of how much extra should be charged. Currently the monthly rent is $1200 + utilities. From your previous experiences, how much additional rent should be charged?

Your thoughts are much appreciated.