Ally gets along well with LM because she's their age. Also it seems Lauren is close with Jade as the former has once commented "I love you" on the latter's IG when she posted something funny.
LOL at "Little Mix only following 5H now on Twitter." Little Mix do not have personal Twitter accounts so it's not a big deal. The LM Twitter is mostly management.
The girls do have individual Instagram accounts, and both groups follow each other over there.