hmmm, well you can try using your username and password from playfirst and see if that works. you should also contact playfirst about it so they can either refund you or hopefully help you more on the issue.

oh yes she can play your diner. all she will have to do is open up the game just like you do. or were you talking about playing your diner with you? if thats the case all she has to do is download the game if she hasnt already and go to multiplayer and look for your diner. but make sure that you put the diner on shareable to others that way she can access the diner as well as other people. hope this helps