I did what you said and I found this:

this.VoterAnswers.Voters[0].ResumeUID = new Voter().GenerateResumeUId(8);

Unfortunately I couldn't find where the GenerateResumeUId() function(?) is.

For this reason I decided to go another way:

I made up this query which copies the values of the specific field in the dbo.vts_tbVoterAnswers into dbo.vts_tbVoter.ResumeUID

UPDATE [SurveyDB20652].[dbo].[vts_tbVoter]
SET [ResumeUID]=[[SurveyDB20652].[dbo].[vts_tbVoterAnswers].[AnswerText]
FROM [SurveyDB20652].[dbo].[vts_tbVoter], [SurveyDB20652].[dbo].[vts_tbVoterAnswers]
WHERE [SurveyDB20652].[dbo].[vts_tbVoter].[VoterID]=[SurveyDB20652].[dbo].[vts_tbVoterAnswers].[VoterID]
AND [SurveyDB20652].[dbo].[vts_tbVoterAnswers].[AnswerID]='163'

I ran the query and it worked smoothly. I even did a resume and then a save to see if the value is replaced. It works.
Now I want to turn this query into a Stored Process (or perhaps shove it somewhere in the existing stored processes) 
and have it ran from there. This way the original code remains the same in case I want to revert :)

Still Im not sure in which Stored Process should I put it. I was thinking 'vts_spVoterResumeSession'  but that means it will
kick-in in case the user wants to revert, not save. I need to find the process which occurs on 'Save Progress'. 

Any ideas?