Creates the Aligning Recommendations with Children's Actual Clinical and Emergency Needs and Determinations Act (ARC-ACEND). Provides that if a child who is the subject of a custody or parenting-time dispute has a serious medical condition, all recommendations made by guardian ad litem, child representative, evaluator, mediator, or other court-appointed officer are deemed provisional and may not be used by the court until a qualified medical provider certifies, in writing, that the recommendation is consistent with the child's clinical needs and medical best interests. Requires that if a qualified medical provider determines that a provisional recommendation is not consistent with the child's clinical needs or medical best interests, the recommendation must be modified to at least the minimum extent necessary to achieve consistency with the recommendations of the qualified medical provider. Provides that nothing in the Act may be construed to limit the court's authority to order additional or more protective modifications if consistent with the child's clinical needs or medical best interests, but the court may not impose less protective measures or measures inconsistent with the qualified medical provider's recommendations. Requires that if the court alters the recommended modifications of the qualified medical provider, it must rule in writing and specify the reasons for the alteration, and the qualified medical provider and the child's primary caregiver must be given an opportunity to respond before the order becomes final. Requires medical consistency for children with a serious medical condition to supersede all other considerations, including but not limited to, geography, parental preferences, logistical convenience or feasibility, or generalized notions of co-parenting balance. Provides that for any child with a serious medical condition, it is per se contrary to the child's medical best interests to be separated from a safe parent who is primarily or predominantly responsible for the child's day-to-day condition-related care, monitoring, or condition management. Provides that this presumption may be rebutted only by clear and convincing evidence, supported by qualified medical testimony, that separation is medically necessary for the child's safety or clinical well-being.