The Collective Agreement provides for six non-instructional days, four of which are teacher-directed. Admin has one non-instructional day that they are responsible for planning and this single day cannot be split.
Teachers have professional autonomy to choose professional development activities that are of the most value to them and are not required to be on site on these days. Splitting the days restricts these opportunities and interferes with teacher autonomy.
Furthermore, teacher-directed non-instructional days cannot be used for items that are Admin responsibility like school goals and planning.