Keep getting 3rd partied

Also, with all these movement abilities and on average very high ttk values, you most often can disengage any fight,  you don't need to commit to it. If you're being really 3rd partied (technically, if you already killed your opponents, then it's not a 3rd party anymore, you're 1x1), you should disengage and either leave altogether or, if you're still bloodthirsty, try to become the 3rd party - instead of being in the sandwitch, try to turn your opponets to shoot each other and then eliminate the stronger one first, clean up what's left and get ready for round 2 (2 more squads coming).