The idea is, if Bills don't have in any row my order's order number I know there haven't been genereated a bill for that order.
This works fine and all, but then I realized the data is a bit... "**bleep**y" as in for the field 'Bills'[OrderNum] most of the rows have just 1 value in it (Format: Text) "0001234" for example BUT the field may have MULTIPLE OrderNum's in them like "0001234, 0001235, 0001236".
I supposed CONTAINS() might be able to work as a regular expression but that is not the case, I suppose it tries to look at the whole thing so now in Order[ID] I have "0001234" and if this ID is in one of these fields with multiple ID's in it I get FALSE for the ID to exist.
Sorry if explanation is a bit messy but I tried to make it clear where the problem is. I have tried doing with FIND(LOOKUPVALUE()) kind of things, but just this one is picking my brain now a bit too much.