Populate 2nd combo with alpha based on 1st combo with 2 columns of numeric codes

Ok, here is the challenge. I have 3 combo boxes. The first I populated with regional institutions. The second is for districts in that region, but I only have numeric codes at the moment. Lastly, the 3rd combo box will display the name(s) of local institutions in that district. It seems to me I would create a loop based on the district code in combo #2. The kicker is if the user does not make a selection( in #2 or #3) they get everything for combos #2 and/or #3 (default values). I honestly am racking my brain in how to even approach this since I'm new to vba programming. The first combobox only has 57 unique values. So that was easy enough to code. The rest however...

Column 1 is the district code(5 digits), column 2(5 digits) is the building code and column 9 is the name(aplha varies). The name column is mixed with all 3. The first 57 values are combobox 1 so that's done. The rest have to be filtered. does that help? The spreadsheet is on a different computer not on the network here at work.