Hello,
I don't know exactly if this is what you're trying to do, but...
Couldn't you use the expand attribute of lists? For ex.
>>>a = ['usrc','recs','user',resu']
>>>b = ['brea','reab','earb','baer']
>>>a = a.expand(b)
>>>print a
['usrc','recs','user',resu','brea','reab','earb','baer']
Hope this helps. (Though it probably doesn't...)