Sometime after 4pm, each Order member* will get a discrete patronus from McGonagal with the following message:
"We have been compromised. Communication black out until all clear. Safe houses to be evacuated and relocated."
The general guidelines for the black out are:No official group communications,
Recommend against group wards
Members would have a secure system to communicate with McGonagall and Moody as needed
Members are discouraged from speaking about Order business with others
Individuals would have their own safety plans/contingency plans, which allows individual players to decide what it looks like for their characters
Despite lack of official communication between members, by July 5 it would be fair for most Order Members to assume/know that the Marauders are somehow involved in the compromise. (Given context ahead of time, it is very appropriate for the Prewett Twins and Florrie to put the pieces as soon as message goes out.)
*NB: Remus, Peter, and Sirius will not receive these messages. Order supporters may be notified at the discretion of their Order contact.
[Please free free to use this to write little reactions for your characters like a mini IC/OOC post.]