Is there a way to add text and signature after it has been submitted and signed?

My team is developing a process for risk acceptance between departments and IT. We have a preliminary process that currently lives in a Word document and we wanted to see if it can be put into a more automated process in Smartsheets. There are 2 parts to the document that each require signatures/sign offs.

The process is as follows:

1. Department fills out required information and the request of a change they want to do. We are still unsure who this will be filled out by, could be Department Head or departmental IT/application owner.
2. Department Head reviews the request and signs off. After this sign off, we want this to go to IT with all of the form information along with new boxes for IT specific additions.
3. IT will review the form submission, add their recommendations and have another sign off and have all of this recorded.

I've investigated 2 methods to possibly get this done:

1. Use 2 forms. Form1 gets filled out by Department and authorized by Department Head. Using workflows, set up the authorization from Unit Head and once approved, transfers form data to Form2 with same fields as Form1 but added new fields for IT use. Issue I found was that Form2 would not pre-populate the data on the actual Form so that it can be reviewed. This doesn't seem to be an available function in Smartsheets yet per: https://community.smartsheet.com/discussion/40861/auto-populate-data-in-forms unless there has been a recent change.
2. Use Document Builder to integrate Docusign into the form process. My colleague has been looking into this but has run into the problem of having the form data go to PDF but can't get it back onto Smartsheet. I will try and get more detailed info on this but would the process be possible described above be possible using this method?