Two phone numbers on one Apple Watch

Saw a YouTube video where a guy had his primary phone number attached to his Apple ID and cell phone (SIM card with cell provider in an iPhone)

Then he activated his eSIM phone number with the same cell carrier. Once the 2nd line (eSIM) was activated vis its own standalone Apple Watch plan ($10 extra only for a current user with T-Mobile).

He did some steps to get his main watch and apps working perfectly fine on the Apple Watch, and then he was also able to receive and send texts / calls from either his SIM card (primary cell # & his 2nd line).

text and call notifications would be identified by which line was being contacted as well. I just can’t seem to get the setup done correctly….

I reset my Apple Watch, set it up as a “family account” for myself as a second line. Accidently saw it made it a child account and me as the parent for the watch. And it messed up my dob… regardless set up the watch and finally got it to work with my 2nd line… but now I can’t use it with my primary cell # / Apple ID. Did I do this backwards? This whole thing is giving me headache but it’s definitely worth the effort. I need two lines for work and personal applications that require two actual cell lines for 2nd/3rd factor verification. I already have a watch and don’t wanna get another burner phone.

I appreciate any advice or help if someone has an idea… feel free to keep it as simple terms as possible. I’ll be sure to lookup anything suggested before doing it anyways.

• Tony