This mechanism supports multiple parents on terms. However, it needs the migrations to include its callback, within a process pipeline like:
# In migrate_plus.migration.reinstall_terms_foo
process:
parent_id:
-
plugin: skip_on_empty
method: process
source: parent
-
# This step is needed to transform the terms parents to usable values.
# Without it, all terms will be at level 0 in the target vocabulary.
plugin: callback
callable:
- '\Drupal\reinstall\Plugin\migrate\source\ReinstallTermSource'
- 'getParent'
-
plugin: migration
# Notice the reference to the current migration.
migration: reinstall_terms_foo
parent:
plugin: default_value
default_value: 0
source: '@parent_id'