Is there legal documentation between SRS and the host family?

Yes, the Host Agreement.

When registering with SRS as a host family, you will be asked to sign a Host Agreement. This document will go over all the guidelines pertaining to the responsibilities of the host family, and it must be signed by someone that is over the age of 18 – typically the head of the household or the homeowner. With this agreement, we ensure that the host family is protected and knows exactly what SRS requires.