I own a small juice bar, with two seats behind the counter for me and my employees, and a piddling number of seats for customers that are usually occupied.
My brother has genetic disorders and his 18 y.o. daughter genetic and developmental disorders. Every week she comes to the juice bar to visit me, and I cheerfully always treat to whatever she wants, free of charge, but she never leaves after finishing her juice.
She sits behind the counter and plays with her phone for hours, until I have to close up the shop at night. She says that she can't go home, as she loathes her dad (he smokes too much and the whole condo reeks, for instance).
Many customers look rattled when they see her, and some of them think she's my daughter! When the store's busy, her sitting behind the counter hinders the workflow. How to communicate to either her or my brother that as much as I care for her, her presence behind the counters is an issue when the bar is crowded? I don't know how to say it without upsetting them.