Just make lots of Infestors and use them to mind control Mengsk’s army so you can use them against Mengsk.
That is one way to bring unity to the Dominion. All Mengsk’s units needed was a new paintjob to join the good guys.
Emphasis on the quotation marks.
I didn’t quite go to that extreme, but there was a play through where I decided to capture everything big that I came across during the mission.
What was interesting is when I did an F2 -> A-move into the final base with a maxed out Zerg army + the captured Terran units, in the end only the captured units were left. My entire Zerg army was obliterated.
Well they are all basically Mercs, even the units that didn’t have a mercenary option in WoL (Reapers, Medics).