Set tab values for second signer after first signer completes

Hi,

I’m still in sandbox.

My use case is we send the envelope to a signer. After they complete signing, we need to fill other fields for the second signer before they view the document. 

I’ve implemented sending the the envelope to the first signer with pre-populated fields. But after the first signer completes and I update the fields for the second signer, the second signer still sees those fields as empty.

I’ve tried both 

envelopesApi.updateRecipients()

and

envelopesApi.updateTabs()

Neither of those made the fields pre-populate when the second signer loaded up the doc.

Is this possible to implement? How should I go about it?