@frymark I would recommend that each document that is being signed in your specific scenario has a unique envelope. There are several ways to create the same envelope experience..
1.Create the first envelope, add the Recipient, add fields such as Name and Text fields with date validation for the Start Date fields, then send. You can then copy that sent envelope and alter the Recipient while keeping the same fields etc, repeat for each new envelope/new Recipient.
2.Create a Template. Templates allow for envelopes to be created based off a boilerplate with the same structure of emails, fields, settings, but the Recipient can be set uniquely each time the Template is used to create a new envelope.
Generally speaking envelopes can contain as many Recipients as you want but multiple Recipients are more typical for an entire approval process. The benefit of a unique envelope per Client is that there is no shared details such as Client Name, Phone, Email, etc that Clients may not want to share with individuals they do not know.