I live in Greece and babes 1st language will have to be Greek as that is where babes will be spending most of time, nursery, school etc, I will speak to babes all the time in english and will also have english books, songs, etc, my friends here have all done this and the kids whose mums do not speak much greek have better english accents than those who speak greek to them indoors, it is also important to try to teach them to read and write in the other language as well. I had some friends whose mum was French and they could speak fluent French but give them something to read and they didnt have a clue.
good luck to all of us!!!!!!