Customer Card - Billing only vs Billing and Contact details
Customer cards can be made up of a billing card or billing and contact card.
So the fields have to be able to handle both scenarios.
Billing Card Only
If the Customer card has only the billing card, then the merge fields will use this information for both the contact and billing information in a document template.
Example of the Template for the Customer card above
Contact and Billing Card
If the contact has both a Billing and contact card, then they will show independently.
Example of the Template for the Customer card above
Merge fields
Billing Card Merge fields
Contact card merge fields