add device to "find my" on a windows desktop

Hello stefanmaine,

It sounds like you are wanting to add a device to Find My on a Windows computer, right? If you have already added the phone to your account in Find My, you will only be able to add it to one account.

When you set up Find My, it will allow your device to be set up with one account. You can find more information here:

Set up Find My on your iPhone, iPad, iPod touch, or Mac

"How to turn on Find My for your iPhone, iPad, or iPod touch

1. Open the Settings app.
2. Tap your name, then tap Find My.
3. If you want friends and family to know where you are, turn on Share My Location.
4. Tap Find My [device], then turn on Find My [device].
5. To see your device even when it's offline, turn on Find My network.* 
6. To have the location of your device sent to Apple when the battery is low, turn on Send Last Location."

Regards.