Clarification: What I meant with splitting party is in fact not splitting the party itself, but rather that the party is present at two different places at the same time. I.e. game mechanic wise, only one party, but group A is at place X and group B is at place Y.
If two game mechanicwise parties are made, I tend to see that both (probably both, at least) parties are using party chat.
Sorry for the misunderstandings!