first of all thanks Slor and all the others for your efforts and volunteering
I really like this rule and hope all captains/players can remain flexible in trying to complete as many matches as possible:
5. Substitutions are allowed at any time. Everyone would like to see the matches played, so if you have a player who can't find the time, bring someone else in. Teams should, however, should do this in the right spirit (I don't want to find out that you are intentionally holding better players back to use as substitutions.)
good luck to all and have fun