Data Validation - Named list issue

[Mark Hanson]

Good Afternoon All,

I was wondering if you could help me.

I have 2 drop down lists where if I choose Option A in list 1 it
automatically updates list 2 and vice-versa. (I found an excel sheet one
this discussion group with really helped me figure this out)

The numbers list users the following source data:-

=OFFSET(Data!$D$2,0,0,COUNTA(Data!$D:$D)-1,1)

At the moment this chooses from the list and goes from D2 to D149, however
my list contains over 170 names. Can any one help me alter the formula to
include the other lists.

Many thanks in advance.