How does one 2 seperate database instances in sync??

Situation:
2 Hp9000 oracle based applications running same application Both instances are requiring their individual ownership of data.

Need to be able to keep both instances in sync, preferrably on request. For instance today I would like to add all of europes 'new' data to the us instance and vice versa.

possible same parent for child relationships.

Need to insure data integrity.

Any and all replies thanks in advance.
John Hawkins

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