Dual SIM card
How can I stop my daughter from using a SIM card with my phone number on another iPhone
Question marked as
Best reply
Please check the eSIM configuration Using Dual SIM with an eSIM - Apple Support
Also make sure it's not your Apple ID logged on her phone.
There's no other other way she could be using your phone number unless she got a cloned SIM, which is not a thing for a family. Bad guys do that in order to use a phone without getting a bill.
Maybe you could also call you carrier support and check with them if both your lines are all good.