BW Field routine, DSO lookup

Hi Experts,

I'm having a situation where I need to get Notification task text into service order operations.

In the notification DSO I have 2 key fields, I'm using this DSO to get the task text.

However, my source DSO ( service operation ) contains only Notification Number as the key, Source DSO does not provide sequential task number.

The lookup for Notification DSO will be happening between DSO ( service operation ) to the cube level.

In this case kindly advise how to approach?

Thank you.

Regards

Las.