TMs are there to only let one person in with the bags. If you are the only adult with some kids, I'd guess they'd let the whole group go in but if there are multiple adults, one will go in while the other walks around the locker building with the rest of the group.
The party will join back up after the lockers.
This might be a spoiler if you don't want to see any of the HP world before you walk in, so click at your own risk.
Maybe this will help - check this link
https://www.google.com/maps/@28.473...4!1szez51V5hm-cEQN5joCp__w!2e0!7i13312!8i6656
It's an older image, Dragon Challenge was still open, but the Hagrid's entrance is in the same place.
Orient yourself so the train is on the right side. The Hagrid's line will go in the same direction, right in front of the train headed towards that building that has the Hogsmeade sign. That building is one of the locker areas.
Click the screen to walk forward so you are in front of the locker building. The person with the bags will go up the steps and put the bags in the locker. The rest of the party continues past the building and makes a right when they pass it.
Click forward a few steps and turn to face the big flags - that's where the Hargid's queue 'officially' starts. You'll also see the exit for the lockers. You can probably see that there isn't a lot of room here for the non-locker group to wait for their locker-going partners.
Not pictured is another locker building that is to the left of the queue entrance. You might be directed to that one instead.