Is it possible to create an outer join when I link the data from a HF to a transformer ?

I would like to know whether it is possible to create an outer join when I link the data from a HF to a transformer.

The situation is I retrieve data from source table and transform them by using a transformer. From the very transformer, I need to take data from a hashed file so I create a link between the HF and the transformer. By default, the link is based on the equality of the 2 columns. But I need to take all lines existing in the transformer no matter if they match those in the hf or not.

I wonder if it's possible. If so, how to do so