I have been asked to create 3 dropdowns, the first list has sixteen items on
it. The contents of list 2 depend on list one so I want to write a formula
or something so that whatever is in list 1, the corresponding list appears in
list 2. I then need to repeat this for the final list.

I tried to do data validation using IF function but got excel would only
allow so many characters/iterations of IF.

Is there a way to get excel to accept more characters or for the formula to
be written "smarter" so that I can point any of the 16 entries in list one to
the corresponding list in the second dropdown?

I have looked at the Contextures site but I'm not sure which function there
would be best to use.

Is there a way to get data validation to deal with this or are there other
alternatives I need to consider?

Many thanks.