I think the break even point is between 8 and 10.
Once tickets are linked, I don't think you can unlink them, but you can make them inactive and have other tickets be active (so that you use those for park entry and not the others)
I don't know if you have to add on the new ones, before you can make the old ones inactive though.
It depends on how many trips. Current DVC PAP is $514 with tax. Two 3day tickets without park hopper would be about $600 on UT. 10day wo park hopper is selling for 366.
For us, we hold on to the no expiration tickets to bridge between AP.
Prices are readily available on Disney's website. The answer can vary depending upon whether or not you want park hopping, access to waterparks or both.
Also, does anyone know who to call to get our current no expiration tickets unlinked from our Magic Bands?
This cannot be done. Disney tickets have always been sold as "non-transferrable", meaning that only one person can use a park ticket. Now with the MDE system, tickets are permanently linked to each individual.
If you decide to buy Annual Passes for a certain time period, you can always keep the non-expiring park days for future use. They should remain attached to each user's MDE account for years to come.
Until first use, tickets can be stored in your MDE account and moved to others in your party. Once first used, they are tied to the person and can not be moved.
There will be a "reassign" link if you can move them or a "Non-Transferable" indicator if you can't.
Depending on your circumstances, MDE can do it manually. I moved my father from my MDE account to his own account after he had used his AP. I could not do it on the website, so I called MDE. The service rep had to submit a request for the tech people to unlink the AP from the band linked to my account and link the AP to his new account. Took 24 hours. The only reason they did it was because it was going to be used by the same person.