Need Dropdown to Auto-Filter Table AND say CUSTOM when table is manually filtered

I need to Auto-Filter a table using a dropdown menu (in order to filter in various pre-defined combinations with one click).

Also, when the table is manually-filtered (using the table header button), I need the dropdown cell to display "CUSTOM COMBINATION" or "MANUAL FILTERING" so that it does not display a misleading value.

I'm guessing I'll need to learn some VB and use a Control for this? Any help would be appreciated.

Workbook attached.

Thanks!

hi can anyone explain how is this being used, and its syntax.
I am referring to SelectedGroups

=IF(SelectedGroups="Other_Combinations",COUNTA($C$11:C11),IF(SelectedGroups="B&C",COUNTIF($C$11:C11,"B")+COUNTIF($C$11:C11,"C"),IF(SelectedGroups="A&D",COUNTIF($C$11:C11,"A")+COUNTIF($C$11:C11,"D"),COUNTIF($C$11:C11,SelectedGroups))))