When my parts fight like that I seem to be the one stuck with the headache from it. Grrr! I feel you on this one!
Sometimes it helps to have an agreed on mediator (internal or external).
Do they let you know what they are fighting over or can you just feel them fighting? Mine typically fight over time with massage T or "sibling" rivalry type fights. journaling can help too, gives everyone who can write a voice. Those who can't write can make pictures or appoint a scribe.
Other helpful things we have done along the way:
Set up an external calendar where parts can schedule time for themselves.
Agree on a set of rules before the fight
journal
Make sure everyone has their own space (inside and/or outside the body)
Get to know everyone even if you don't like them or trust them.
Set the firm, uncrossable boundaries and why they are there. make them as clear, simple and exact as you can.
Work on patience

Hope it helps