Integrating Campaign Response from two SFDC instances

Summary:

Hi there, we have a client that has two SFDC instances and needs to integrate campaign and campaign responses to both of the instances accordingly. I see there's a limitation on only one connection is available. Is there any other method we can achieve this goal? I am sure there are instances where several SFDC instances are required for the business and in this situation.

Content (please ensure you mask any confidential information):

Connecting campaign and Campaign response with two SFDC instance.

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):