Hello JN01,
Welcome to the community!
I think there might be a little trial and error required. As far as I am aware, the lines should be listed by phone number in your My Account. From there, you should be able to determine which phone number has the different plan. With that information, you would need to try each SIM card to determine the phone number associated with it. You should be able to determine the phone number of the SIM following the steps outlined here.
You should note this forum is community-driven and not intended as a venue for customer services. We would not have access to customer accounts so we would not be able to identify the SIM cards for you. If you would like additional assistance with those SIM cards, you would need to contact customer service. They can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀
Cheers
