Search and Return Value From Different Table

Evening all,

I was wondering if anybody had an ideas on this conundrum:

I have a table called Master Product that needs to retrieve a field from another table Called Variants. I currently use the following formula (SKU is the variants serial number and used for indexing the records for when I want to search them.):

first(select Variants where SKU = SKU).'Variant 1'

'Variant 1' is a combo box with three choices in it: Colour, Size and Weight. When a choice is made ie Colour, a second combo box Appears called Variant 1 Colour. If they were to select Size a different combo box appears called Variant 1 Size. The user then selects the colour, size etc. How would I return the Variant 1 Colour Value to the field in the different table?

Many thanks in adavnce.

Alex