Purchasing DSO data get overwritten by Datasource 2LIS_02_SCN

Dear Experts,

I went through many discussions and SAP notes but couldn’t find solutions for my issue so starting this new thread.

I have custom DSO ZPUR_O01 which gets loaded from 4 purchasing Datasources 2LIS_02_ITM,

2LIS_02_SGR, 2LIS_02_CGR and 2LIS_02_SCN. The Key of the DSO is Purchasing Document Number and Purchasing line Item no (similar to Standard DSO 0PUR_O01).  Now whenever the ROCANCEL = R comes for Datasource 2LIS_02_SCN it overwrites data of fields mapped from all other 3 datasources in DSO active table.

Standard DSO 0PUR_O01 also get loaded from same 4 Purchasing Datasources and have same keys.

I would like to know did any one face the similar issue before and what could be the possible reason behind this?

Thanks,

Amit Rajput