I have encountered the following and would like to know if this is a bug or is this intentional, and whether there is a workaround.
We are using a SmartCapture form on CloudPages to capture Leads. The form is linked to a sendable Data Extension and is used as a Journey Entry Source ("Event Source data extensions must be sendable by linking a sendable data extension to the contact record."). Send relationship is set as EmailAdress relates to subscribers on SubscriberKey. The journey doesn't send any emails, it just creates a Lead in Sales Cloud. Lead is created, everything is fine, and in Sales Cloud it is given a proper Lead ID, for example 00Q1t00000ABCDEFGH. Now later this lead can be triggered to another journey (this can happen manually from Sales Cloud, or programatically from Sales Cloud). And when the lead is triggered from Sales Cloud into another journey, this time with email send activity, the email is sent to that lead, but it's added to All Subscribers list with SubscriberKey = EmailAddress. Which mean's it's taking into account the relationship set up in SmartCapture, not the one set up in the second journey, which works fine in case the lead is created manually in Sales Cloud (then Sales Cloud LeadID = SubscriberKey).
Can someone please clarify:
How does the Contact Builder know that the Lead who enters from Sales Cloud is the same Lead that was captured by SmartCapture?
Is there a workaround that will allow to use the Sales Cloud LeadID as Subscriber Key for when lead enters the second journey?