I bought my daughter a Apple Watch se with cellular. She does not have a iPhone so it is set up as a family member through my phone. how do I add mobile data to her Watch with a different mobile number to mine?
You can link it to your O2 number but the only way your daughter can use it is with her own iPhone and a pay monthly sim, as I've repeatedly said.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.