Help with INDEX / MATCH

Hi All,

I think I more or less understand INDEX / MATCH now.

But instead of matching on 1 field, I would like to match on 2 fields.

Basically, looking at the attached xlsx spreadsheet, I currently have A and B matching C (from the data sheet) and entering the correct values.

As these are surnames, there are duplicates and it is currently only matching on the first surname and not the remainder.

So I would like to match it against C and D - So only complete A and B if C and D matches.

Then secondly, you will see I have made drop down list from the data on the data sheet (C and D) and D is populated (sort of) only with matching data from C. But this is not working correctly for duplicate surnames.

If someone can please point me in the right direction or if someone can possibly assist me to get this sheet working correctly, I would really, really appreciate it.

Thanks so much.

Jakez