How to modify a template and use both old/new in the same library without interference

Question

OK first Thank you for reading this and hopefully being able to help me out. I got dumped this project on my desk to update two different templates already published in
share point(2010) years ago. The original developer left the company 4 years ago. Since then anyone that tried to do anything with them made a big mess. I have done some heavy reading and am stuck on few issues.
Please note the templates were created IP 2007 and I will be using IP 2007 to modify them. The temples have a small amount of C# that does not have to be changed. There is also a digital signature linked to them.
After some heavy reading this week. I figured that I need to edit the template from Share point(2010)/IP(2007) and not copy the templates to a different location laptop/desktop
because that will ruin the digital signature. There is also a large volume of submitted forms from these temples. The new version of the temples will be heavily modified deleting rolls columns changing names. My understanding is that since I want to keep the
old submitted forms the way they are and still use the old template to open them. I would need a second version of the original template with all the visual modification to still use the original template's C# digital signatures and any other file that runs
in the background.
The plan:
1)Turn off the automatic update to forms/template when a new version of the template is created.
2) Copy the existing template (.xsn) file to a new document folder in share point(same network).
3) Change the name of the .XSN file that I copied and modify it??????????? Will keeping the same name interfere with the old template/C# digital signature ect? I would like to change to something like SameName_version_2015 for example. or will changing the
name cut the link to the old C# digital signature? or will it get modify the background files and break the old template/submitted files.
4) Publish the new template in share point.
5) Change the data connection to a new directory that I wish to submit all files.
Please advice am I missing anything? and help me understand my step 3 better. Also I would love to get a better understanding of how i can backup and recover everything. Do I simple copy unmodified .XSN files somewhere and publish them if things goes wrong?
Do I need to backup anything else?
I am open to options if I can create a test folder in the share point for safety.
Once again THANK YOU for trying to help.

Answer 1

Hi, thanks for the reply!
Just to follow up for what we did to disable the delete function for maintaining table records. We hided the Delete button by adding a "MODULE disable_delete" code in Screen Painter. So now only adding records to the table is allowed.
Thanks,
Jenny