The woman that talked about her companion tipping generously out of her means is exactly what my perception regarding her. She is right on every count but you veered too much with no significant wisdom to guide her. You filled your swimsuit with coins so you could tip her? That was a ridiculous idea I ever heard, you are not leaving tomorrow, you insult more than being a responsible guest. An appreciated verbal comment is all that needed, you do remember the bartender then you tip at the end of your stay just like another commenter said. (I do understand your concern she’s overtipping and you feel uncomfortable matching that amount. I don’t see why you couldn’t have that discussion) She already did, but her friend just insulted her saying if she couldn't put up then she would pay her share too. You continued that if she  can't be persuaded then it is up to her. The woman was concerned that her friend just don't understand like you, I sure don't want to hear anything from you