restore signer who was previously replaced

[Lila5E78]

How can I replace current signer by previous signer ?

I get a message saying 'you can't add an individual who was previously replaced'. 

Is there a way to restore previous signer ?

[SimonESATS]

by default the original signer can still sign.

[Patrick31132604fdv7]

I tried getting the original signer to sign the document and he got a response saying:
XXXXXX@XXXX.XXX has been replaced by another participant and is not a party to this document anymore.

How do we restore original signer? Replacing email to original signer's adress also return an error.