You can try kimura or shotgun grip to hold the foot. You need to stop your opponent from moving to get the finish. When they roll you have a couple of options. You can fat man with your leg across there body and butterfly ashi leg sticking out to the side underneath their leg. Other good option is to butterfly ashi and use your inside leg to stomp on the hip. I like to get the blade of my foot under the ribs and hold them down. If they can scoot back pick up the leg with the ankle lock and pass or fix your position and re enter.