Sam,

I noticed that nobody answered. Sometimes getting the important facts into
and described in a posting is tougher than solving the problem. Your
post had not enough on what you have (data and table structure) and what you
want to do, and too much on the (possibly wrong) way you are thinking of
doing whatever it is.

Combo boxes us generally for poplulating fields, yet you do not describe any
such desired action. It sounds like the goal is to look up a price, going
first to "Contract A" if it exists. You didn't say what attribute(s) you
are searching by, and "the search" is at the heart of what you are asking.


Taking a few guesses, here's one thought, if you are just trying to look up
and view a price. One big table with all of those contract items in it.
Have a field which designates which contract it is from. You said that "A"
is a subset of "B". If this is absolutely always true, 100.00% of the time,
then the two choices would be "AandB" and "Bonly" and you would enter the
"AandB" items only once. If not, it would be simplest/best to make your
choices "A" and "B" and just make 2 records for common items. (A data
structure purist would make the choices "Aonly", "AndB" and "Bonly", but that
level of abstraction would probably cause more problems that it is worth)


Then, when you do the search, and get the one or two entries, sort it so
those in contract A are on top. Ditto for a combo box if you define a data
loading /. field population mission.

Hope that helps a little.