Like somashekar, my first thought was that this belongs in the BOM. This aligns with OP's option 2. Based on the organization that I work with, the challenge may be that two different groups are involved. For example, marketing or Customer Service may be tasked with the instruction book, packaging and other collateral pieces (called OOBE - out of the box experience where I work), while the Engineering team is tasked with changes to the product. It is easy for one group to be out of synch with the other group.
Perhaps, the product change control (ECR/ECN) process may benefit from having a checklist item related to these marketing collateral pieces so that the question is at least asked when changes are being implemented. Additionally, if not already the case, an owner should be assigned for the marketing collateral, so that when a change is needed, the team making the change knows who to go to.
BTW - I think the software team's suggestion is a red herring in the post. The way I read it is that the software team has an existing system for source control and is offering it as a solution to the other teams.