dynamic validation

On one worksheet I have a table such as the table below. On another worksheet I have a bunch of lookups that are based off a couple of unique values. Name is repeating, but identifier is not. On another sheet, I need a dynamic drop-down list of all identifiers for a given name. For example, if...

What I want to do is create a validation list that lists the names of all the excel files in a specific folder. Then I want another validation list that lists all the worksheets in that excel file. Is something like this possible? I would like to implement it on a spreadsheet I am working on...

OK, here is what I am trying to accomplish: I have one cell (M12) that uses a data validation list that is tied to all the names of the worksheets in the workbook. I want the user to be able to select the worksheet they want to use in the first validation list, then have a second validation list...