Complex sentence: The Animorphs are unsure of what to do with David; although Ax draws attention to the fact that they can use the box to give him the power to morph, the Animorphs vote on whether or not to do it.
Split into simpler sentences: The Animorphs are unsure of what to do with David. Although Ax draws attention to the fact that they can use the box to give him the power to morph, the Animorphs vote on whether or not to do it.