Linked UD table not adding new rows


So the I’ve been asked to make a change to the Part customisation, this has already been set up so that it links to a UD table. This UD table already has rows of data in it.

I’ve been asked to add a checkbox and textbox to the screen which I’ve done and then bind them to some available columns in the UD table.

If I load a part that’s already in the UD table and make a change to the checkbox and textbox I’ve bound to it the columns update fine.

But if I create a new part or modify a part that’s not in the UD table then it doesn’t add a new row into it.

Is this something I have to do in the customisation or should it be doing this as standard?