Did you ask for a list of requirements for a retirement extension? That's what you need. The fact that you are changing is not relevant, because it's just an application for an extension based on a different reason.
When switching from marriage to retirement, your wife will also need to be present for this extension, but will not need to be present for future applications.
Most immigration offices require many other forms they will provide to be signed, and some require things like your lease, and other various items.
Don't tell them you are changing when you go to ask, as you will just confuse matters. You want the requirements for a retirement extension. That's it.