Item Type Lookup with Arrays

I would like to use Item Types as a way to calculate quantities for transportation projects. I am using an "ItemNumber" field to lookup the item description as well as other information about the pay item. from a spreadsheet located in the workspace.

There are many instances when the same microstation element may have multiple pay items. For instance, a manhole we would pay for the manhole and the cover separately. I can make a property type called "Pay item" and use this to create an array of pay items on the microstation element. However, when I do this the lookup functionality fails. Anybody else try to do something like this with any success?