Can't include additional contact entity fields in bulk email

For the accounts in our system we have a primary contact and a secondary contact setup and I would like to send bulk email to the accounts primary contact to ensure both their account information is accurate but also some key information (fields) from the primary contact and secondary contact such as name, email, phone etc.

While I can achieve most of this setup and display all the account information along with the primary contact information I can't figure out a way to display the secondary contact information other than the just the name field.

Currently the secondary contact field under accounts is a look up field into the contacts much like the primary contact field, although the primary contact field only allows the selection of a contact which is linked to the account already and my custom secondary contact field lookup will allow a user to select any contact in the system.

Any help would be greatly appriciated.