The modify button only works for about 20 minutes after the review is published. Adding addendum further down the thread is dependent on punters reading a review and ALL the comments - most don't.
So what? A review is ideally about one experience which you can post about. As southcoastpunter says you can add to your own review about a second meet (assuming the rating is unchanged)t. If you're so precious about your oeuvre, then post 2 reviews.
How do you know how punters behave reading your reviews? I would say if someone can get through one of your reviews (I struggle with them TBH - they are wordy and need signposting IMO) then they can make it to the end of the thread.
Also, what are you going to do if you rate the punts differently?