Cancel a change of responsibility?

I am the account holder, there are 3 lines total, the other two are authorized users. A few days ago we thought it would make sense to separate on of the lines from our plan. I called to initiate the change and was told the other user had 30 days to claim responsibility for the line. The other user has not done that. We’ve decided since that it makes sense to leave things as they were, with all 3 lines on my account. If we take no action, will the line stay on my account? That seemed like the outcome, but the rep did mention my billing cycle closing soon and not having to pay for the third line past then. The outcome we do not want is the other user losing access to their phone number.