DSXchange

You can't use a 'combo' action as it requires full metadata on each link. Use separate links, one for insert and one for update so you can have the appropriate metadata on each link. And use a reference hashed file to prequalify the action.

If the target is any dbms, you can set the values in the backend.

This can be done using a trigger.

You can create an 'on update' trigger which does

:new.col5 := :old.col5;
:new.col6 := :old.col6;

There are many other ways to handle this.

Only if that's the way you always want that handled.

For this one job, sure. The trigger however would be a forever 'solution', regardless of source or circumstance.