I am the manager for a group for my university, and I find that it would be pretty useful to rerun contests from the gym inside the group (so we get our own ranklist while doing the contest and everyone can participate at the same time).

The problem is I think I can only change the global contest start time (sorry if this is not the case -- didn't want to try and mess everything up), which would render the contest inaccessible for a period of time. I can see two ways to solve this problem with the current system:

1) Make a private training copy of the original contest. Has the disadvantage of reuploading a bunch of data to the servers every time we want to run a group contest, and metadata for both contests will become separate (updates in the original contest will not be visible in the training contest).

2) Change time for the contest at the exact desired start time for the group contest. This is pretty hacky, and has some obvious concurrency problems (what if two people are trying to do this at slightly different times?)

Is there an official recommendation on this matter?