setting up family sharing with kids that already have an icloud email

Hi cricket103,

If your children already have Apple ID accounts, you'll want to invite them to your Family Sharing group, versus creating an Apple ID for them while creating a family group.

The following steps below show how to invite your children:

"Invite people to join your family

You can be a part of only one family at a time.

On your iPhone, iPad, or iPod touch

1. Go to Settings.
2. Tap your name, then tap Family Sharing.
3. Tap Add Member.
4. If your child doesn't have an Apple ID, tap Create an Account for a Child. But if your child already has an Apple ID, tap Invite People. They can enter their Apple ID password on your device to accept the invitation.
5. Follow the onscreen instructions.

On your Mac

1. Choose Apple menu  > System Preferences.
2. Click Family Sharing.
3. Click Add Family Member, then follow the onscreen instructions.

If you're using macOS Mojave or earlier:

1. Choose Apple menu  > System Preferences, then click iCloud.
2. Click Manage Family.
3. Click the add family member button (+), then follow the onscreen instructions.

If you have multiple Apple IDs, you can invite each of your accounts to the group, so you can share purchases from your other Apple IDs with your family."

Those steps and additional detail are from this article: Set up Family Sharing - Apple Support Let us know if that helps or if you're still encountering issues.

Take care.