Well, the single picture you uploaded was shot at f/10 and 1/160 second at ISO 200; how about trying what OUGHT to be a totally safe speed, and going to 1/90 second; surely 1/90 will give even illumination, even with bargain basement triggers. If not, go to 1/60 second. Do not worry, indoors, f/10 at 1/60 second at an ISO level of 200 will be fine; the FLASH will stop any motion, and that exposure of f/10 at 1/60 at ISO 200 ought to be well below any ambient lighting.