If I’m understanding correctly, you could do this without needing a Help Ticket.
First, activate the new phone by installing the Republic app and signing into the Republic app with the Republic account credentials for the phone number you want on that phone. Activate the phone and in the process you’ll have the option to get a new number or move the existing phone number to the phone. Move the number.
The new phone will then take that phone number and the old phone that had the number will be de-activated.
Then pick up the phone that was just de-activated and sign into the Republic app using the Republic account credentials for the other old phone you mentioned had died. Activate this phone so that it takes on the inoperable phone’s number.