Routine Query

Hello, I have a question about some DSOs joining. I have three DSOs
DSO1
DSO2
DSO3

DSO1 and DSO2 have 1 to many relationship

DSO3 is blank yet

I want to bringing records from both DSOs in to DSO3. I can not do multicube and or infoset.

Some one told me i can write a end routine to gather records from both sides. is that possible then how? i know how to write a regular routine but not this kind where i can get multiple records from one dso based of of record coming from another dso.

please let me know,
Thanks.