I am not completely sure about the requirement here. But, since the question is about using multiple column values in after.field, yes, there is a way.
What I did was, use a string variable say, e.g. comb.f, now, concatenate all the values you need and assign it to this field. Now, use this field on your report layout as after.field.
It has worked for me, so why not give it a try.
Unless you try to do something beyond what you have already mastered, you will never grow!