lost iphone is being used for location sharing

I left my iPhone in taxi a few days ago. It is protected with fingerprint, a long pass code and double authenification, so I am not too worried about my data. As soon as I was back in my hotel, I checked out "find my iPhone", but unfortunately it was offline, and has not been back on-line since then. I put it into lost mode from my iPad.

My iPad location symbol is now constantly on, and under location sharing I get the message that my iPhone is being used for location sharing. I do not understand how this can be possible as find my iPhone still says that it is off-line. In the hope that someone will find it, and ring the number that should show in the lock-screen if and when it comes on-line, I have not as yet wiped the device.

Can anyone explain to me what might be happening with the location sharing? I wonder if location sharing on the iPad will remain permanently switched on until I remove the iPhone from my account. I shall be grateful for any ideas.