Concatenate Empty Tables

Hi i know ive seen answers already but they dont seem to work
Im trying to join tables depending if they satisfy rules. The columns match but when one fails the concatenate wont work , or if theres only one of the rows it fails too
Added a picture for reference

@barrycasey welcome to the KNIME forum.

I think you will have to use maybe a combination of case/if switches. Maybe combined with a group by and count to check for the number of rows. As it happens I collected some links about import and switches maybe that would help.

Then the best thing would be to create a minimal viable example that represents all your challenges so the community could have a look.