Hi Julie,
This particular action you're looking for is not part of the Cvent Salesforce App. As it relates to updating campaign member statuses, this particular sync is one-way, only, ie: Cvent to Salesforce.
Commonly, our customers who utilize salesforce campaigns tend to also use salesforce or other systems to handle event reminders and other communications, so we don't often need see the need to update Cvent statuses. Additionally, if there's a particular reason why Cvent would need this decline information, I would suggest reaching out to your client success resource to discuss options on how to decline registration for invitees and it reflect in both systems.
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Ryan Costa
Mas33United States
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