How can a configure a second controller so two children can play a game together

Hello, how are you? On your case, I recommend that as a parent you configure your child's account so that he has more security when playing, you can configure it in the parental control.
I have an 8-year-old girl and I have her account set up so that she can play with children that I have added.

Hi, I don't now about the Forza specifc but you can use the both controller to play together only you need is callibrate the both controller, one like controller one and the second like controller to, if you can play forza together you can play another
games with you liked play together, a Game by the way with I recomend to you play with your wife is Sky Froce Aniversary and Reload Version, both is the greate games to play in two people in same place

You can get two configurations for the Elite controller, you'll see the switch in the middle so you can change it.

When using the accessories app you can edit both configurations for your personal play style and what you feel is best for you. My 1st configuration is to adapt to most FPS shooters so I can use the A and B buttons as paddles, so I can use the thumb sticks
all the time along with the hair-triggers and thumb stick curve being instant and the second for Racing.

It's a matter of personal preference and how you as a player navigate a game, it may take a while, but you will find the right layout for yourself.

Regards

Thank you very much for your reply. There must be something in the settings, as I can add myself, so I can play with one of the children, but I can't add the two children together. I don't want to allow them access to everything, but do want them to be able to play games together, as their own login. They're allowed content up to 12 years and are allowed Minecraft multiplayer and Realms and to create and follow clubs, in the Xbox Family App. It must be in these settings, but not sure what the magic combination is.

This hasn't really changed..in fact its gotten quite easier. You can still go and purchase a disc that your 3 children can take turns playing. Additionally, you can purchase one digital copy that two of your children can play at the same time together.
There has to be a limit on the number of people that can access one digital copy.