You exactly describe multiaccounting. If your players have no time to send attacks, then that is the problem of your alliance to fix the gaps, but with legal ways. To share password with the leaders of your alliance to send mass attacks, is a violation of the rules and extremely unfair for the defending alliance.
Ridder Huma Now, the Travian Responsibles can continue to ignore the multiaccounting in a big style. They even admit to do it.