Hey, magenta4891931! I'm not 100% sure I completely understand the question, so I'm going to provide both possible answers -- sorry if this is confusing!
Legacy Pay As You Go is grandfathered, so we won't be able to switch the plan types on your respective lines. If your concern is purely about the physical device, you should be able to swap SIMs between the two phones, if they're compatible! Basically, the phone number that is currently Legacy Pay As You Go will still be Legacy Pay as You Go, and the phone number on the current Pay As You Go plan will still have that plan.
Hi Marissa, thanks for your response. Yes, I figured out that I can swap the SIMs but I really would like switch the phone numbers associated with the legacy PAYG plan. Do you work for Tmodile? Will Tmobile will be able to tell me definitely if this is possible, I understand that this is probably not a common question?
Hey, magenta4891931! I do work for T-Mobile! I'm sorry for the confusion about your question. While it might not be the most common ask, I understand what you'd like to do, thanks for clarifying!
Although you could turn the line that is currently a Legacy PAYG plan into a new Pay as You Go plan, since the Legacy PAYG plan is grandfathered, you won't be able to switch the other active line to it. I wish we had better news for you!