Unfortunately, you cannot combine tickets to "purchase" an AP. In addition, if you had wanted to UPGRADE one of those no-expiry tickets to an AP, it would have had to have been done within 14 days of the first day that the ticket had been used and the AP would have had an anniversary date that was one full year from that date of initial use.
However, the PP was correct that you can email ticketing to find out how many days remain on each ticket.
Given that the original bearer of some of the tickets is now deceased, Disney may convert those tickets so that the remaining entitlements can be used by someone else, but each ticket would retain the number of days. There would not be a way to "combine" all of the remaining days on a single ticket. This conversion would have to be done in person, at a ticket window or guest services location in one of the parks or Disney Springs.