[SalesForce] Record count – related list

There are 2 ways :

• Formula field
  
• Custom Inline VF page
  

If you are ready to compromise on related list field visibility and prioritize reports, then its possible on reports without creating any new field.

You can't directly add a grandchild object as a related list on an object - there has to be a direct relationship. You can certainly pursue the Visualforce route if you wish.

Alternatively, you could add a new custom lookup from the Docusign status object to Opportunity, and then use Process Builder or a trigger to populate that lookup with the parent Opportunity's ID. This would create a direct relationship which would allow you to include the related list as usual.