It won’t let me add family member

Yes that is happing to me did you find a way to fix it?

Hi emauniak,

Welcome to the Apple Community, where some of us do our best to help each other troubleshoot.

Wondering where you have been trying to add the kids.

Seems each family member will need to have their own Apple ID.

If you have Family Sharing, it seems you can have up to six of you ok.

This Apple support article "Set up Family Sharing on iPhone":may help:

Says:

Create an Apple ID for a child

1. Go to Settings  > [your name] > Family Sharing > Add Family Member.
2. Tap Create a Child Account, then follow the onscreen instructions.
3. The child’s account is added to your family until the child is at least 13 years old.
4. See the Apple Support article Family Sharing and Apple ID for your child.

Here's that complete "set-up" article, including how the kids can accept your invitation and join, etc.

https://support.apple.com/en-au/guide/iphone/iph223f61318/13.0/ios/13.0

AND

For more on Setting Up Family Sharing / invitations etc.

https://support.apple.com/en-us/HT201088

Other articles that may help:

Use Family Sharing to provide parental consent for your child's existing Apple ID

https://support.apple.com/en-us/HT208506

Set up Screen Time through Family Sharing on iPhone:

https://support.apple.com/en-au/guide/iphone/iph00ba7d632/ios

Use Family Sharing with iCloud

https://support.apple.com/en-au/guide/icloud/mm0b5e79e99b/icloud

Share purchases with family members on iPhone

https://support.apple.com/en-au/guide/iphone/iph4cd8953e2/13.0/ios/13.0

Turn on "Ask To Buy" on iPhone

https://support.apple.com/en-au/guide/iphone/iphec188a85b/13.0/ios/13.0

Hope this helps you :)