Column Combiner: Delimiter with blank charachter

Hi,

maybe a silly question, however I am stuck: I need to combine a changing number of columns to a single one. So I tried with column combiner which works fine. However I need the delimiter with a blank character. In my use case a ", ".

No matter what I try, string manipulation etc. there is no blank character added or the blank is just left out.

This is my test output:

However, what I need is:

A, B, D or

A, C, D

The other thing: missing columns are quoted with a “?”, however they just should be left out.

Thanks for any hint.