Currently the selection of contact will only be one contact at a time. If multiple contacts needs to be pulled in, this will have to be done via the relatonship.

Thanks for Your Response,
Do You Have Any Docs Or POC on this topic or Any Nintex Docs Links, So I can refer that, Please Share with me

Hi I don't have any POC available but you can read more about our relatonships here: https://help.nintex.com/en-US/docgensf/DeliveryStorage/Relationships.htm

You would need to create a lookup for the object you are running from and have a child relatonship to the contact object.