Can't turn off iMessage on daughter's family connected devices

It could be in screen time. Turn it off and you should be able to edit the iMessage app. When I turned off screen time on my son’s iPhone and forgot to turn it back on, he was able to edit the iMessage app.

Hello cdsmiler81,

It sounds like you aren't able to turn off iMessage on both the iPhone and the iPad. Which iOS version is currently running on the iPhone? Do you know if her devices have parental controls set up and managed by someone else? You can take a look at this to get more information:

Use parental controls on your child's iPhone, iPad, and iPod touch

Regards.

Perhaps obvious, but I’ll ask anyway...

Are you sharing a single AppleID between devices - or have you created a new AppleID for your daughter’s use?

Having re-read your original post, are you attempting to confine SMS/MMS text messages to just the iPhone?

SMS/MMS messaging is effectively relayed to/from the iPad, from the iPhone. This function is controlled by the iPhone amd is configured in iPhone settings.

If this is your intention:

Settings > Messages > Text Message Forwarding - set to OFF - or explicitly disable your iPad from the list of devices.

Also ensure that Messages in iCloud is disabled on the iPad:

Settings > [Your Name / AppleID] > Messages - set to OFF

If instead you seek to disable all messaging on iPad, you’ll need to sign-out from the Messages App on iPad:

Settings > Messages > Send & Receive > [AppleID] Sign Out