Renter wants to hold a child's party in the backyard.

[Kim Livingstone]

A renter wants to hold their little sisters birthday party in the backyard of the property. Sister doesn't live on the premises. The building is quiet and all renters have been informed of this. The renter made the request in writing, per their lease, but I'm not comfortable with having kids running through the backyard or building. Has anyone experienced this and do you have any advice?