Raising my youngest kids bilingualy

When we lived in California Luisa always spoke Italian to them and I spoke English.  So when we moved to Italy Julia the oldest had a fairly easy time transitioning to Italian and her English is still pretty good.  She is now 9 and doesn't really have any problem speaking either language, though she has gotten a bit of an Italian accent.  Giovanni, had a harder time moving over into Italian.  He was not quite four.  At the preschool he only spoke English for the first couple of months and then more or less suddenly made the switch to Italian.  Now he is much more comfortable speaking Italian than English.  And he is a little resistent to speaking English, but since I mostly speak it to him he is keeping it up though at a slower pace than he might.  With him it may be a constent struggle, we will see.   We are not about to let it go.  They both must be fluent in English as well as Italian.  In the next couple of years we will have to decide on a third language.  Not sure what that will be. I suppose the choices are French, German or maybe Chinese.