Is it permissible for a Muslim volunteer group to organize events that include minor Sharia violations, such as music and slight mixing, to prevent other groups from organizing the same events with much greater Sharia violations, such as songs, extensive mixing, dancing, and alcohol?

It is not permissible to approve of, witness, or aid in a reprehensible act, as Allah Almighty says: "And do not cooperate in sin and aggression" (Quran 5:2) and "Then do not sit with them until they enter into another conversation. Indeed, in that case, you would be like them" (Quran 4:140). However, the principle of balancing interests and harms should be observed, whereby the lesser of two harms is tolerated to avert the greater, and the lesser of two benefits is foregone to achieve the greater. If the benefit of organizing Islamic events outweighs their harms, then there is no objection; otherwise, the default is to prohibit events that include impermissible elements.