Coalesce, combine (5)
I believe the answer is:
merge
I believe this is a double definition.
'coalesce' is the first definition.
(I know that coalesce can be written as merge)
'combine' is the second definition.
(I know that combine can be written as merge)
(Other definitions for merge that I've seen before include "Come together as one" , "Make one" , "Join into one" , "Fuse" , "Combine, coalesce" .)