See:

Adding a new row to a table in a document with formfields:
https://www.msofficeforums.com/word-...html#post38312

Adding a new row to a table in a document with content controls:
https://www.msofficeforums.com/word-...html#post87989
https://www.msofficeforums.com/word-...html#post38461
https://www.msofficeforums.com/word-...tml#post145675

Neither approach requires the use of a command button - which can of itself be problematic.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]