It is probably too soon to conclude with a 1* overall. The best advice is to review fairly and factually for each of the factors that is reviewed. If she for instance has given good pet care and left the home clean and tidy she should get credit for that, and then explain in the comment section what was good and for what * are deducted.
Otherwise it might backfire as an emotional review can be negative while a factual review would normally give an impression of a level-headed and resonable member regardless of issues being brought up. What we say about others is important - and often not only a reflection of the one we are talking about but about the one saying it. So keep it factual and fair.
I suggest that you inform member services that the sit has been curtailed and explain why so that the sit end date is changed .
You may also want to raise a member dispute about the sitter having a third party to stay without your permission. Providing the camera evidence and messages . This is to protect yourself from any complaints from the sitter about the sit being curtailed. THS will investigate and potentially remove this sitter from the platform .
Information about member dispute process has been discussed here :