Feature: creator of a group should be able to decide on visibility of annotations (own vs group)

I know this might be a bit tricky but I ran into a major methodological issue regularly when students/people were annotating the same video (at the same time). The annotations of other steer the own annotation process way too much into one direction (it really fixes meaning, interpretation, focus) and narrows down the perspective on the content drastically.

Especially as teacher I would like to have the option to decide when I want the students to also see the annotations that others created. So, they are first invited to annotate a video without seeing the annotations of others while the creator of a group (e.g. teacher) can at some point decide to make all annotations visible. I consider this to be crucial, especially for use cases linked to #cotanz but would like to have it included in #vortanz as well. @anton.koch, do you think this could be implemented as part of the group management? It would be even better if the creator of the group/teacher could still see all annotations (e.g. make use of the cotanz features) but members only see the annotations of other members when released by the group creator, but that's not crucial.