Retrospective Party Wall - is there any point?

[Thatsnotmy2021]

We live in a terrace house. Two years ago we had the chimney stack on our roof terrace removed as part of some renovation works. The neighbours were happy for us to do this, however they didn't want to sign anything as at that point their house wasn't officially owned by them (It was still owned by their deceased mother and the paperwork was still going through).
So, I don't have any paperwork to say they were happy for us to remove the chimney breasts, but I did take some photos.
Now, the paperwork has come through and our neighbours officially own their home. They are happy to sign something, but we don't know what they should be signing.
I've done some googling and a party wall agreement is really for something pre-building works (in case the neighbours didn't want us to do the work).
Is there such a thing as a retrospective party wall agreement? And would not having any paperwork impact on any future sale of our home?
Would love to know if anyone has any experience of this.

PWA is in case anything gets damaged during the building works. No point doing it after.

A bit late now, but photos should have been taken before in case of damage.

I doubt very much a missing PWA would have any effect on selling. Planning permission etc. might do but as long as everything was does properly then I can't see any issue there, either.

if all good now then I think it's a waste of time.

Did the chimney breast impact their property? Have you got any legal advice on how long they could make a claim for after? Did you get their confirmation in writing etc.?

Unlikely to be a massive issue, but I’d probably get some legal advice, and if there’s any chance of it being even a slight issue for a future buyer weigh up the cost of getting something formally in writing now vs possibility of having less interest in your house when selling.

More of an issue likely to be building regs sign off if needed though?

Thank you for your replies. Yes, we did take photos beforehand and everything has been signed off by building control. It's been two years since the work was finished and there's been no damage.