Since I'm using different s/w its slight hard to explain but can somebody explain how to merge/add two rows and bring the result into new row but only where I want i.,e.

abc
def
ghi

I want to merge abc+ghi and call it say -abc2 my new row should be
abc2
ghi
...

Can sombody suggest the logic, I have now hit the dead end and just no go a clue..