If you're lucky, you'll get one photo in which they're all looking somewhat straight ahead and standing still.
(When I tried it the other way around and I just got the free rotating camera. Mouse Look Move your view around, separate from the direction your Sim is currently looking. Dracotaurus1235, try holding down Shift and then while still holding it down press Tab.
Ideally, he should have a good camera that allows you to zoom in and out. Control the mouse cursor and the User Interface while in First Person Camera. Direct the photographer to stand front and center, far enough away so he can get them all in the shot. Make sure you direct them to stand in a straight line, so they are side by side. You can also select the option Try for Baby with a ghost. The ghost can make your sim pregnant with Woohoo.
Now, this sounds creepy but fun on the other hand. In Sims 4 if your female sim character builds up a relationship with a ghost, they can have a child.
This is important, because with autonomy on, trying to keep several Sims in the same place is a little like herding cats.