Not able to find the losing record's source system and source system reference value

We have three parties with three source system and source system references. After merge, the master party retains all these three source system and source system reference values. Therefore, we are unable to find out which source system belongs to the losing record and which belongs to the winning record. Please let us know the root cause of this issue. We need a way to track the cross reference of the losing and winning record. If it is a tool limitation, based on previous experience, let us know of the alternatives we can use to achieve this requirement.