Average Non-duplicates Only For Filtered (non-hidden) Cells

how to calculate a simple average after removing duplicates. The trick is the average must work after the spreadsheet is filtered. I was able to make it work with a VBA script but the users don't like this since the numbers don't automatically update whenever they apply a different filter.

What I need: average (mean) value of (in this case age in years) based on unique ID#s that doesn't include duplicates (some ID#s are in database several time):

ID#
Age
Filter Options

11111
27
Option A

11111
27
Option A

[code]....

So if I filter by Option C, the cell with the average should return the average age of only the filtered ID#s but without the duplicates.

Correct age w/no filter: 56.8
Correct age w/option C: 59

What I have tried using: (reason for difference in cells on the equation, I condensed it in the above example so A=C and B=G)

This array works but will return hidden and non-hidden cells b/c of average(if), so it doesn't work with filter:

{=AVERAGE(IF(C3:C13C4:C14, G3:G13,FALSE))}

Also have tried the Subtotal 101 function, also with no luck: Note, a simple subtotal101 fxn will not work b/c even when I filter there will still be a few rows that are duplicate and need to be removed before averaging

=SUBTOTAL(101,(IF(C3:C13C4:C14, G3:G13,FALSE)))