get along famously (with someone)
To have an exceptionally good relationship (with someone); to get along very well (with someone). I'm glad you finally got to meet my brother—I knew you two would get along famously. My grandparents have been married for over 50 years and they still get along famously!
get on/along ˈfamously
(old-fashioned, informal) have a very good relationship: My mother and my mother-in-law are getting on famously.