Aligning the control fins with the sustainer wings puts the control fins into the turbulent wake created by the forward wing fins. This makes the control fins less efficient, and in a worst case scenario, the steering force of the control fins could be completely negated, making for a much less stable configuration. Check out the article titled "Increasing Rocket Aerodynamic Performance" by Thomas Salverson on page 42 in the May/June 2019 edition of Sport Rocketry. Essentially (on the right side of page 48) the portion of the fin inside the turbulent wake of the airflow behind a reducing transition doesn't do anything for the rockets stability. It is suggested that while a transition section below a wider payload section decreases the aerodynamic drag on a rocket, it induces a wake that interferes with and decreases the effectiveness of the rockets fins, and these fins should extend out beyond the rockets body until they are in the laminar airflow region beyond the diameter of the transition. I suggest the same effect will occur when the wing and control fins on the Sasha model rocket are aligned, especially since they are more than one body tube diameter apart. You might want to also visit this thread about a "box kite" like fin configuration that doesn't fly stable; https://forums.rocketshoppe.com/showthread.php?t=17929

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Bruce S. Levison, NAR #69055