We've created a custom object "Enquiry" in sales cloud which is child object of "Lead" object. (i.e. Lead represent a unique user)
We've also deployed marketing cloud which is in sync with sales cloud. I want to create a data extension which will be used to send emails on each enquiry. Can I create this data extension in a fashion such that primary key is Enquiry_Id and Lead_Id is mapped with SubscriberKey. (Context - Whenever I create a DE and make any field as Primary Key, Marketing cloud automatically maps primary key with subscriber key).
(Leads are being counted as Contacts in marketing cloud)