Family Sharing - Two Devices One Account

Today I have set up my daughter’s first phone, and setup an Apple ID from my account as part of family sharing. It’s classed as a child account, so certain controls apply. All good so far.

However , she already had an iPad which utilised my Apple ID originally. So with her own ID in place, I moved the iPad onto it also, but the limits I have placed on under Family Sharing are applying solely to the iPad and not the iPhone, which is not the way round I wanted. I signed into the phone originally and then the iPad, so tried the other way round under the premise the last sign in would take priority. But this hasn’t worked.

Any ideas how I could get the controls back on the phone, as opposed to the iPad?

I can’t understand why when both are signed in, only the iPad is displaying screen time etc.

Do they have to be on separate accounts?