Redi, I think this can be done - barely - but it's so ridiculously complex
that I gave up on the challenge even for the fun of it. This should really
be done as a macro, which would be much, much easier.

Do you savvy VBA programs, and do you want to tackle it that way? If so, I
can help with that.

--- "Redi" wrote:
worksheet one:
1 black a b c
2 green b a d
3 white c a b g
4 white d
5 white e h i
6 white f
7 blue g c a
8 yellow h
9 red i a b c

Worksheet two:
1 black a b c
2 green b a d
4 white c a b g d e h i f
7 blue g c a
8 yellow h
9 red i a b c

The formula i am looking for will be on the columns where the letters
are. This will probably be some sort of look up formula, the results of
which will list all the letters based on the colors despite that the
numbers and order will differ.