Link textbox value to verbiage in Word.

[ceeejayy]

In Microsoft Word, I have a VBA textbox ("TBox") and some verbiage in a bookmark field ("BMark"). I want to link the bookmark field to the textbox's ControlSource such that the verbiage appears in the textbox (as the textbox Value). I've failed with multiple different entries into: 1) the Properties > ControlSource box and 2) code on the UserForm. Ostensibly and in simple descriptive terms, there should be this outcome:
[ TBox.ControlSource = "BMark" ]
From what I've read, it SEEMS as though this should be possible but now I'm uncertain. There's nothing sacred about storing the verbiage in a bookmark field: some authors suggest linking a table to a ControlSource and that would be fine. Whatever works. The textbox is a VB editor object i.e. is not a form control.
Any suggestions would be greatly appreciated.