«Help, my daughter's girlfriend is a slacker!»
It's the question of all parenting questions: Am I allowed to bring up children that I didn't bring into the world myself? Of course! That would have been the answer a few decades ago. Of course the neighbour reprimanded us if we were too loud outside and disturbed her. Nowadays, people make a fist of it when children in wet winter shoes run around on the train seats and keep quiet, annoyed. I think: your rules apply at home. Tidy up half an hour before your girlfriend has to go home. And if you have a stomach ache, you unfortunately have to give up the sweets as a reward.
The girl probably feels as overwhelmed as we adults do when we want to help with the washing up in someone else's kitchen. You can expect the visitor to help tidy up, but you should formulate exactly how. Give the girl a clear sub-task: «Please put ... here in ... Thank you. Now ...» You can get things moving with good music. How about bringing the afternoon of play to a cosy close with a short story, a simple board game or a hot chocolate? They can look forward to this while they are tidying up.
Yes, you can. Next time, tell the little simulant as soon as you greet her that this visit to your daughter - at this point they make a regretful expression - will unfortunately be her last if she doesn't help tidy up in the evening. In the evening, tell the two girls about half an hour before closing time that it's now time to tidy up, and make sure that the lazy friend also lends a hand, at least the first time.