Agregation during transofmration from DSO to DSO

Hello everyone,

In one DSO I have key fields like Claim ID, Activity ID.

Rows with unique Activity id - is most detailed, suppose I have 40 mlns. of records.

Claim ID can be same for several Activity IDs. There is about 2 mlns. of unique Claims.

I am trying to agregate data during transformation from DSO to DSO.

To make 2 mlns from 4 mlns with key figures summation excluding Activity ID but keeping distinct Claim ID.

How to do it?

Thank you.