I can't track my daughters iPhone 6 from my iPhone 16 PM

jonmac wrote:

Is it as simple as the iPhone 6 being incompatible with find my?

No, the iPhone is not incompatible with Find My.

If Find My is turned on on the iPhone and you have Family Sharing enabled, you should see the iPhone in the Find my app on your own devices.

Open the Find My App, tap on the "Devices", then scroll down to the section for your daughter's devices the iPhone should appear there.

If you are trying to change the location that is being shared as hers in the People tab of the Find My app from the iPad to the iPhone, that needs to be done directly on the iPhone in question.

If the option is grayed out, then it would seem you have applied Screen Time Parental restrictions.

On the iPhone 6, go to Settings ➜ Screen Time ➜ Content & Privacy Restrictions ➜ Location Services, and make sure its set to "Allow Changes".

Forgive me if I'm stating the obvious but since you don't provide details as to what you've already checked, presuming you did set up Find My on her iPhone, have you checked that iPhone to confirm that "Share My Location" hasn't been turned off?

jonmac wrote:

Thank you, sorted now. It was as simple as toggling off block daughter making changes, following your instructions, then making the iPhone her default tracked device, then toggling back on block daughter making changes. Working perfectly now, thanks for your help.

You're welcome. Glad it worked out.