Is it permissible for charitable organizations to dispose of the funds allocated for sponsoring orphans and spend them collectively on all orphans, including those not sponsored, and not give the orphan his full sponsorship?

It is not permissible for organizations to distribute funds to anyone other than those for whom they were designated, because they are agents for the owners of the funds. They must return the funds that were distributed to undeserving individuals to those who are deserving, based on the Prophet's (peace be upon him) saying: "Upon the hand is what it has taken until it fulfills it."