As a mum of twins I find mine fight more over a separate item each than a big shared eg Playmobil hospital between all 3 great success,wooden farm great success but when one had Playmobil ambulance the other the medical helicopter major rows.
It's lovely I'd check that they have the space for it and maybe suggest they need some princessy figures to go with it as those seem a bit flat but it's a great idea.