It is easily possible to send more than one document to a recipient at one time, within a single email and signing flow.
To upload more than one document or template to be sent as a single SignRequest, simply add them per usual on the primary "upload document" page.
You can add multiple documents here (see screenshot):
Once sent, the recipient will receive a single email with all of the documents included. Once the signer signs the first document, they will be automatically directed to sign the following document, until all documents have been signed. Then, they will be able to "Finalize" the SignRequest.
Once a document is finalized, all parties involved will receive an email with copies of the signed documents (as PDF's), as well as copies of the Signing Log (also as a PDF).
If you have any other questions, you can submit a ticket to the help center.