They changed how projects work, originally you invited observations and the observer accepted the invitations, and there was a sort of bulk invite tool that project curators could use. But people apparently got tired of endless invitations, so they changed it so that you didn't have project invitations, but anyone could add any observations to projects they were in, so long as the observer hadn't opted out. But they got rid of the bulk invite tool, probably worried that it could have rather drastic effects if there was uncontrolled bulk addition to projects. So project curators have a tool to find suitable observations that they can manually add, and another to find unsuitable observations to find any that have got in, but shouldn't be there.
There is also an option, that can be turned on to automatically gather up observations, but this can have rather drastic effects as we found with the Whau River project where a slight logic change meant that 40000 observations were added, and due to other unresolved bugs the (now renamed) project can't be deleted and there is no way to automatically remove the extraneous observations!
But using a bit of magic, I have added all the observations that match the area definition.
Tony.