I have multiple excel data files e.g. a.xls, b.xls, c.xls, etc. & one master
data file.

a, b, c, etc are in one directory & master data is in another directory.
Also sometime I may have only a & c file available but no file b. How do i
transfer the data from a, b, c, etc to master data file without opening any
one of them. I know it can be done with ado connect. but i'm lost with
codings.

Please advise.