Hi RyvLusMom,
Make sure you have covered all of the steps and conditions in this resource when setting up Screen Time for the daughter that you can't set limits.
Set up Screen Time for a family member on iPhone – Apple Support
1. On your family member’s device, go to Settings
> Screen Time.
2. Tap Turn On Screen Time, tap Continue, then tap This is My Child’s iPhone.
3. To schedule downtime for your family member (time away from the screen), enter the start and end times, then tap Set Downtime.
4. To set limits for categories of apps you want to manage for your family member (for example, Games or Social Networking), select the categories.
5. To see all the categories, tap Show All Categories.
6. Tap Set, enter an amount of time, then tap Set App Limit.
7. Tap Continue, then enter a Screen Time passcode for managing your family member’s Screen Time settings.
Note: You can also turn on downtime on demand for a family member, either directly on their device, or through Family Sharing on your device (if you’ve set up Family Sharing).
If your child requests more screen time, you can approve or decline the request in Settings > Screen Time or in Messages.
If you have followed the steps correctly and you still have the issue, let us know if you get any specific alerts or error messages when trying, as those may help us determine what might be causing the issue.
We also recommend restarting your device and keeping it updated as those steps assure you have cleared out any minor software issues and are running the most current version.
Restart your iPhone - Apple Support
Update your iPhone or iPad - Apple Support
If you still have questions, reach out to Apple Support directly, as this may require closer guidance: Get Support
Cheers!