So I loaded my save that had my ship parked on the Omega 4 relay and gave this another shot.
It went like this:
First go:
Specialist: Legion
Second Group Leader: Garrus
Personal Group: Samara and Grunt
My lost member always got shot at the door when they were trying to push it shut. I figured having Grunt would help, but as it turns out Garrus is the key. Unlike Samara as the other leader, he brought his group over to help us at the door.
Second go:
Escort: Mordin
Specialist: Jack
Second Group Leader: Garrus
Personal Group: Miranda and Legion
Mordin I figured was a good candidate to watch the crew because that is what he did on Omega. He protected the weak with overpowering force against the enemy. Also, he is a scientist/doctor thing so having him on board our broke ass ship with hurt people made sense. The secondary team for this part was designed to "distract" and that is all Garrus did on Omega as well. As for protecting my group, we needed a strong Biotic. Who else but the ever powerful Subject Zero? Miranda and Legion are great because Miranda increases the entire sqaud's damage ratings, and Legion (if you got his upgrade) has a ridiculusly overpowered rifle which shreds through that panzy Harbinger (especially when paired with Miranda).
Final Go:
Personal Group: Miranda and Legion
Choose to have a back team to defend the rear. Again, Miranda and Legion make a great Harbinger killing team. Not to mention Legion's sniper is good against armor, and that is all that the final boss is.
With this setup everyone survived.