As a Rover sitter, I have 1 dog in my care that attacks 2 other dogs in my care. How do I report that?
You need to inform the owners. Did you do a meet and greet with all owners and all dogs together? Did they all agree there will be a bunch of dogs together who don't know each other? Did all the owners tell you their dogs are friendly with others and will do well in this situation? Now you have to report back to every owner and explain what happened to these dogs under your care. Good luck.
If you haven’t already done so, first you need to assess if you can keep all of them safe and prevent attacks from occurring. That might mean providing different safety zones within the home and walking separately.
Secondly, you’ll need to inform the owners.
Your profile indicates that you take multiple dogs and your background would lead me to believe that you might be prepared for these challenges , so these two steps might be all that’s necessary.
With some reservation/ hesitation, ... Third, decide if it’s warranted to inform rover support (IMO used to be more helpful and more recently is much less- requiring owners & sitters to submit lengthy documentation and rover didn’t contribute anything at all that helped in any way) & if warranted to inform animal control, who will probably follow up with owner upon return.