Can I install Sims 4 on my childs account?

@Crasher_DK  You can't install your copy of Sims 4 on your child's account; Origin doesn't support family sharing, and the game is tied to your account now.  Even if you had a product code, it couldn't be used a second time.

Normally, the only way to add a game to a child account is to buy a code or a physical copy in a store and register it in the child account.  However, you may be able to convince EA customer support to transfer the game for you.  Even though it's not normally allowed, support often makes exceptions in cases like this where the parent intended to buy a game for the child.

https://help.ea.com/en/contact-us/

If support won't transfer the game, then yes, you can request a refund instead, either through support itself or through EA's automatic refund mechanism.

https://help.ea.com/en-us/help/account/returns-and-cancellations/