Perhaps I should have researched Disney Infinity more, but I assumed the extra characters would be suitable for use anywhere in game for a second player. Not the case. You can only use characters specific to a playset. Having bought Rapunzel and Elsa (my daughter's favourite Disney princesses at the moment), it was very disappointing to find that she could only use them in the central area of the game - somewhere where there is very little to do. Turns out that I need the Frozen playset for Elsa, and the Girl Power one for Rapunzel. Neither are currently available in the UK, and when you do buy these playsets, you get the characters anyway!