Mass-VMs are kind of a weird way to give people information. My recommendation would be to copy the contents of the latest post, delete it, and then write your new post. This will acheive the desired effect.
An even better solution is not to set yourself up for double posts in the first place if you know you are going to need to add something later but well I guess it's a little late for that.
Let me put it this way..whenever i'm not playing the game, i'm either listening to the music for it, drawing something related to it, reccomending it to friends, browsing the internet for something related to it, or any of these at the same time. As for where I first heard of Cave Story... i cannot remember... my memory is horrible.