How to create a drop down list dependent on and appended by multiple drop down lists

[JKiler1]

Hello, all.

Please review the attached spreadsheet. I'm looking for a way to create a drop down list that is dependent on and appended by multiple other drop down lists. In the example provided, you'll see lists next to "Active Test Cell", "Active Venturi Cart", and "Active Water Cart". These are the independent drop downs. Once these selections have been made, I would like to have another list next to "Active Item" that has items from all three lists appended to it.

I created the additional list called "Example_List" to show what should be displayed with the current selections. This would then lead to the items in the tables at the top being populated in cells on another worksheet.

Thanks for any help and/or advice you can lend!