Combining different sets of data

Hi, if anyone can help that would be great...example attached. 3 sheets with different data. Some of the names/initials across the 3 sheets are the same, some unique. I need to combine all 3 sheets into one set of data that aggregates the 3 sets of numbers but also recognises the different initials but groups the ones that are the same? So I have a master list of all unique initials with the corresponding aggregated data. Hope that makes sense. thanks in anticipation.