User can delete match created by admin

There are 2 things possible regarding matches:
1) Clan X challanged Clan y and creates a game
2) An Admin create some matches where the clan leaders can submit scores.

Regarding the 2) there are 2 problems:
a) A clan member can modify or delete the match. This should not be possible. If there is a tournament, the members should not be allowed to change anything except submit a score.

Is there a way to limit / fix this ?

b) If a clan submites a score but the other did not, the match dissapears from the match lists