How do I manage 2 kids account through Family Sharing?

Under family, I created two kids accounts.

Kid#1 - use my iPhone to control the account such as Downtime on and off, it works really well and within few seconds.

Kid#2 - when I do the same thing as Kid#1, sometimes it does not do anything and/or it takes hours or days for changes.

Can you please help me to fix Kid#2 issue?

[Re-Titled by Moderator]

Original Title: Family