Alternatively, is there an existing feature that exists where both parties can put the unsigned document in their own DocuSign and somehow both parties’ signature are only valid/included after the other party has signed?

Thanks again!

Hello ​@mark123456789,

Thank you for reaching out, and welcome to the Docusign Community! We appreciate your question and assure you that we are fully committed to providing you with the best service possible.
When an envelope is sent to an email and the signer's email is associated with a Docusign account, the signer has the option to access the envelope and sign it into their DocuSign account under their inbox. 
In the scenario above, if both recipients want to be the last signers, definitely putting a signing order is not appropriate. Have you tried sending the envelope without a signing order? This way, all recipients will be able to access and sign the envelope at the same time.

Additionally, you may check this relevant article about conditional routing, and I hope this will help.

Conditional routing is the first feature released as part of the Advanced Recipient Routing add-on for Docusign eSignature. This new suite of capabilities will help you automate your eSignature process. Conditional routing lets you route an envelope to different people based on envelope data. This eliminates the need to manually configure the envelope routing or use separate templates, each with its own routing.

This guide provides information on how to set up and use conditional routing on an envelope or template. For introductory information about conditional routing, see Introduction to Conditional Routing.

Note: Some advanced features and options are supported only in specific Docusign plans. Your account plan might not support some of the options discussed in this help topic. For more information about which options are available for your account, contact your account administrator or Docusign Customer Support. Visit our Contact Support web page for contact options to reach Customer Support.

Please let us know if you require any further assistance. Thank you!

Best regards,

Ma. Cassandra | Docusign Community Moderator

"Select as Best" below if you find the answer a valid solution to your issue

Hello ​@mark123456789 

How are you? I'm checking in to see if you still need assistance. If yes, kindly reply here with more context or confirm if the issue has been resolved. 

If you run into any problems, we're happy to help with those here. Wishing you a smooth rest of your day!

Ma. Cassandra | Docusign Community Moderator
Mark as “Best Answer” if this helped clarify things.