Advanced Migration - update nodes
I don't know the exact answer. But maybe this information can get you on the right track.
First the migration process has the ability to update earlier migrated entities, it does this with the help of high-water-marks and timestamps (see Drupal's documentation). Maybe you can do a trick to use this feature. Furthermore there is a lot of good documentation about the migration-process, I recommend this site, an extensive tutorial about the process in 31(!) steps/days, https://understanddrupal.com/31-days-of-migrations or https://www.phase2technology.com/blog/migration-making-it-all-work. Behind it some of the &quot;Drupalstars&quot; from the migration and comprehensibly written. Hope you find your answer there.