See the macro code under the headings 'Add a row to a table in a protected form' and 'An alternative method of adding a row to a protected table' at:
http://www.gmayor.com/word_vba_examples.htm
There is also some code at:
http://www.eggheadcafe.com/software/...documents.aspx
The (partial) solution there envisages adding formfields to the new row as well.