Assuming for a moment that it happened that way, I can see maybe TT managing to get the girls into a vehicle with him. But once they arrive at the shop, then what? He has to single-handedly control, then kill, then dispose of bodies.
. However, if another member of the A family took him to work, brought him to the mall, and back to the shop....
For me the only logical scenario here is that at this point he wanted to get far away from any relevant whitnesses (like the adults from A's family - cause sounds like all of them had pretty strong personalities: so they could interfere for the Rachel's sake, or don't care about the Rachel that much but think less of him whitnessing his wife disobeying him) to deal with her.
To this point the vision of "dealing with her" would include yelling, some emotional blackmail, maybe some insuts, minor to mild physical assault. With that it wouldn't matter if Renee and Julie knew about it, heard about it or even saw it - it'd not give him any trouble with "the adults" while possibly even working in his advantage, as using their presence to humiliate Rachel in front of them even more than "in private".
His plans would go straight to sewer if she wasn't having that and fought back, having more confidence than ever cause in her mind at least Renee surely mattered as a whitness of his behaviour.
I may be wrong but I don't believe in Debra's involvement - cause it doesn't make sense for me.
Her claim about their engagement not being serious sounds ridiculous... at least until you see the marriage record on this guy. So many marriages don't imply that person takes marriage seriously, not to mention some brief engagement. And the speed! Oh my God...
Just my point of view, but instead of her, being crazy in love with him (despite of - judging by those brief descriptions here and there - having much hotter and way more interesting guys than him) and being blindly loyal to him, over her sister...
I see him, likely wanting to appear as better man that he really was in front of her and growing frustration over having to act and pretend at home as well.
This is what I know, what I whitnessed, what saw many times in life (in toxic relationships that luckily didn't end up with murder). So this is what I see here.