Making tables accessible in MS Word Forms Options

Have a challenge i cant seem to figure out. I am making a form that i
want to lock down, only allowing the user to enter text into the form
fields. However, part of the document consists of a table where they
will enter info into a cell then move on to another cell. The problem
is, depending on how much entries they have they might need to add
another row or two to the table. How can i allow this. I know
without a form lockdown all they would have to do is push tab and a
new row would appear. However this is not happening with a locked
form. How can i format the table to allow this??