Error returning results in one to many relationship in Make Query Table

Hi,
I have a feature class with a one to many relationship with a table. They are linked with a common field. I need to create a command that will automatically join the 2 into a new table. From reading the forums it seems the best way is to create a python script of Make Query Table. Is this the best method?

The problem I'm having with Make Table Query is it is returning only the results that are one to many! In the Expression box I've put TableA.commonfield = TableB.commonfield but it only returns the records that have multiple records in the second table, however I have records in the first dataset that have no records in the second table.
I'm trying to get a complete dataset that contains all records in both the dataset and the table.

I'd greatly appreciate any advice.
Thanks
Rachel