Merging and De-duping Exercise

Hi all,

I'm trying to de-duplicate a list of donors that have the same first name (column R below), surname (column S) AND postcode (column AA), whilst also merging data in the duplicates' other fields (unique email address and telephone number) and totalling their donation amount in column N. An example of the list is shown below:

Note that non-relevant columns are hidden and I have included an AFTER sheet to show what I want to end up with

Specifically, I want to keep just the ID of the record that has had the data merged into it (with ID1 taking priority over ID2, ID2 over ID3, etc.). The RowID is for my reference so I can later view which rows have been removed as a result of the de-dupe.

Any help is greatly appreciated.

Thanks