When I first began working as a lecturer, I was doing my M. Phil. in the lab of one of my senior Professors and colleagues. Over this time, I have also diligently worked with His MS research students and closely supervised them. The first MS thesis student of my supervisor, who was my second coworker, coordinated the lab and managed the electronic files of the MS research students. My coworker who had been handling the softcopies after my supervisor's recent death published the work without keeping me as a coauthor. How can I now become a coauthor on these published articles?