How can I transform this SS into this:

Is the red line supposed to simulate an EKG wave form? You can use path editing tools, such as the Scissors tool, to break open the segment of the SS icon that needs to be replaced. I would use the Pen tool to manually draw the replacement segment and adjust the thickness of the stroke so it matches up with the existing line work. Then I would expand the stroke into editable paths and join it to the existing SS letters. It’s probably safest to work on a copy on another layer above the original SS letters.