Hi Beth,
Yes, you're quite right - it is en famille [I 'tested' the anagram]. One of the definitions of en famille is 'at home' ergo 'In'. The use of the word 'ground' is in the context of 'ground up'.
Whilst I appreciate you've experienced some confusion over the mixture of Italian and French, the word 'Milan' is only used to facilitate the construct of the clue.
Kind regards,
Caravaggio