Ok here is more planning. Accomplice stashes their own vehicle somewhere near the place they dump vehicle. He/she transports body to his or her vehicle (in a remote location close to where Michelle's car was found) then dumps hummer walks to his/her vehicle. Or Could accomplice live at the apartments where car was found? Hummer into garage for a moment. Empty body. Dump car then dump body?
Okay, here is another based upon an idea I got from yours.
Michelle pulls onto the street and the kids get out and get ready to go inside with Dad. Since the Hummer is in his name, he might be able to pull this next part off. He says to Michelle, I need to check the __________[ fuse box, water pump, whatever] ..mind pulling it into the garage really quick..."
She pulls it in, and then he blindsides her in some quick, clean way. Then he shuts the garage door.
He takes her phone, puts her unconscious in the Hummer, maybe tied up and gagged.
Then he puts the kids in his truck and drives them to grandparents and takes the phone so it will not ping in his garage all of that time.
When he gets to his folks he does a quick phone check to make sure she did not text anyone to say she was staying there for a bit for him to check the car. Then he receives the text from brother, saying ' Where are you."
That might have spooked him, so he quickly sent the decoy text, hoping it would buy him time.
Now this is where it gets harder. Would he dare drive his own red truck back to his condo? I doubt that. So somehow he gets a ride back to the Hummer, and I think he waits until dark to drive out of his garage.