Delta Extraction Based on Changed records but not based on time in BW

Hi,

We are extracting SALES ORDER header and item level data into 0SD_C03 Cube, for that we are using 2lis_11_vahdr and 2lis_11_vascl data sources.

we did initialize the data and doing deltas every day.

At the time of initialization, for the particular sales order sales manager is not assigned and later it is assigned. when we do delta extraction whatever the SALES ORDER assigned SALES MANAGER is not able to extract, how to rectify this issue.

i think when we do Delta loads it is based on time and Is it possible to do it on last changed instead?

can you provide me the solution to rectify this issue?

Regards

Venuscm