I need to split a taxonomy vocabulary into two different vocabularies in Drupal 7.
I can use the Taxonomy Manager module to move terms from one vocabulary to another; I have tested this and it works.
However, the big problem is that I have a large number of nodes with a taxonomy term reference field that include references to the terms.
This is what it looks like now: Nodes of Content Type X have a Taxonomy term reference (multiple values permitted) to Vocabulary A.
This is what I want to do.
Split Vocabulary A into Vocabulary B and Vocabulary A (which contains about half the terms). [This step can be done with Taxonomy Manager.]
Create a new term reference field to Vocabulary B. [This can be done from the Field UI.]
Move the term references to terms that are now in Vocabulary B in the Term reference to Vocabulary A to the new term reference for Vocabulary B. [No idea how to do this except a lot of manual work.]
Any ideas about how to go about step 3?