This paper proposes the integration of the adjustability concept when designing for humans into an existing body-powered prosthetic hand especially designed for the Symbrachydactyly abnormality population. Adjustability would accommodate a range of changes in hand size resulting from hand growth, especially at early stages of age. This accommodation would reduce frequent prosthetic hand changes and associated burdens. The proposed design is based on splitting the palm of an existing design by e-NABLE and using three connecting pieces of three different sizes to join the split palm. The connecting pieces sizes are based on the sizing guide by Unlimbited Phoenix to allow for changing the prosthetic hand size. The developed design must be inspected for functionality and comfort, while satisfying adjustability requirements due to hand size increases. The integration of adjustability into the design of a body-powered prosthetic hand for the Symbrachydactyly population would characterize a significant advancement in personalized prosthetic solutions. The proposed design exemplifies a thoughtful engineering solution tailored to meet the unique needs of its users. This research emphasizes the importance of user-centered design in prosthetic development, paving the way for more adaptable and sustainable solutions that empower individuals with limb differences to lead more active and fulfilling lives.