In the scenario where you cannot use Response Rules and Actions to write back to Oracle Sales Cloud, e.g. contacts having different brand Lead Ids, it would be good to be able to have a step which populates the Campaign ID and CRM ID automatically, and then allows for you to select the appropriate Lead/Contact Id field and the Member Status and trigger a call to OSC to create/update a Campaign Member.
When a contact is added to a campaign, the first step or after first email step could be the Campaign Assoc step, where the Member Status is set to 'Sent'. Then later on in the campaign if they have performed an action, e.g. submitted a form, registered for a webinar, etc, another step could be added to change the Member Status from 'Sent' to 'Responded'