A male aged about 60 yrs having H/O Hemorrhoidectomy 4 yrs back, H/O excision of huge sinus 2 yrs back and with H/O Ch. Osteomylitis of Rt. Ischeal tuberosity; comes with 3 external fistulous opening viz.A B C and 1 Internal opening D at 7'O clock in anal canal below Ano rectal ring. Please refer images. All openings are interconnected. What should be the approach to manage ?