Renters want to take in foster kids. Helllp

[Gary R Uren]

I rented out a 3 bedroom,  2 bath house to a family with two adults and two children.  The just sent me a text asking if they can take in foster kids. I never dealt with something like that before.  The contract says no one else besides them can be there for over a week so it is my choice,  what options should I consider for this, a rent increase per child, security deposit increased.  They signed a 3 year contract and have an excellent rental history.  Thank you, Gary.