I am trying to: I need to have the Words post type display as a select field in the Definitions post type. All this information is already in a database but everything was tied to the theme. I am using your tool to re-create everything so that it isn't dependent on the theme. I have not found anything in the support docs to help me with this. I will attach a screenshot on how it is currently working.
If that is a Post type, with Toolset Types you should recreate the Post type in Toolset > Post types.
If you recreate it with the exact same slug as your old, PHP manual coded Post Type in the Theme, all those posts will be fetched in the Database and appear again under the post Type > All Menu in WordPress.
https://toolset.com/faq/how-do-i-convert-existing-custom-types-and-fields-to-types-control/
Now, Toolset Types offers one possibility to connect posts to posts.
This is a parent/child relation.
One Child Post type can have One parent (of the same type) and one parent can have many Child posts (of the same type)
This is described here:
https://toolset.com/documentation/user-guides/creating-post-type-relationships/
https://toolset.com/documentation/user-guides/many-to-many-post-relationship/
Having the Selector is only possible if you were to set the Post type that will appear in the select field as a PARENT to the currently editing post.
And it is by default not in the Sidebar but below the main content.
This will allow you to set ONE parent for your currently editing Post.