The adult service system does not adequately meet the needs of autistic adults, prompting families to continue their supportive roles. Siblings frequently assume these roles when parents are no longer able to do so, often without preparation or planning. We received feedback on the proposed Siblings FORWARD (Focusing on Relationships, Well-being, and Responsibility aheaD) program concept, which would involve 6-7 individualized sessions over [approximately] 3 months and would facilitate siblings' proactive future planning involvement with their autistic family member. Siblings FORWARD would bolster siblings' skills, knowledge, and self-efficacy to engage in future planning with their family members. We report on perceived need for a sibling program and feedback on the proposed program goals, content, and design. Adult siblings (n = 13), autistic adults (n = 6), and service providers (n = 17) participated in individual interviews or focus groups. Data were systematically coded and analyzed using directed content analysis. Siblings, autistic adults, and service providers expressed high enthusiasm for the Siblings FORWARD concept. Participants indicated that the combination of skill-building and education would promote continued, collaborative future planning that persists after the formal program ends. They had positive impressions of the program concept, goals, content, and design, including the telehealth delivery model. Siblings and autistic adults reported wanting to participate in Siblings FORWARD. This uniform, strong enthusiasm for the Siblings FORWARD concept warrants moving forward to examine preliminary acceptability and feasibility. Ultimately, greater sibling involvement in family future planning may improve autistic adults' functioning through improved continuity of care and support across adulthood.