How to show all (child) contact records for two opportunities associated to each other as part of si

We are using Siebel 8.2.2.4. There is a scenario where 2 opportunity records are associated to each other via single record on intersection table (e.g. CX_OPTY_REL) 

Both opportunity records have contacts associated with them as child records. 

Requirement is to show 

1) All contacts of both opportunities together in single view\applet.

2) Generate a single XML Message (based on Integration object) with both opportunities and associated contacts?

How to achieve these requirements? Any help would be appreciated.