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Within a form, I have a field that enables users to select from a list of customer ID's.  However, I need to filter the list using a child table with additional attributes, so the list I'm presenting the users with contains what looks like duplicate records.  

Do you have any suggestions for an approach I can take for limiting the list of customers to only one occurrence of each ID?  

I've pasted an example below and attached the image as well.  Essentially, I need to filter against customers from the table whose key is in col A, made up of Cols B-G.

When I display the customer number in the pick list, the list as it looks today is as follows:

0000000150

0000000410

0000000410

0000000430

0000000430

0000000445

0000000445

0000001000

0000001000

0000001000

0000001000

0000001000

0000001000

But for this specific purpose, the user only cares about the customer number in column B, so I'd like the available values to be (eliminate dupes):

0000000150

0000000410

0000000430

0000000445

0000001000

I cannot just filter off of the table containing the customer numbers, because I need to filter against some of these other attributes in cols C-G.

Any suggestions regarding an approach I can take?  Thank you!