Watch and Phone on different carriers....

Okay, so I have an iPhone X through ATT.... My mother-in-law bought me an Apple Watch Series 3 LTE through Verizon..... Is there any possibile way to use the LTE on my watch while still haveing my ATT sim in my phone?

There is a line on her account that the LTE Watch is associated with that’s also an iPhone 10, and my iPhone X is unlocked. They have a sim and when I put it in my phone it registers the watch to LTE but if I do this I have my ATT account and number that I get everything through.... See my issue here? :/