The Salesforce connector is a feature that allows you to integrate Marketing Cloud Account Engagement with Salesforce, a customer relationship management (CRM) platform. With this connector, you can sync data, activities, and campaigns between Marketing Cloud Account Engagement and Salesforce. You can only have one Salesforce connector at a time, which means that you can only tie one Salesforce account to one Marketing Cloud Account Engagement account. You cannot have multiple Salesforce accounts linked to one Marketing Cloud Account Engagement account, regardless of the number of accounts, the edition of Marketing Cloud Account Engagement, or the support from Marketing Cloud Account Engagement. Reference: Salesforce Connector, Connect Marketing Cloud Account Engagement and Salesforce