Try a chicken wing a day like Kendals Delta has got in her pictures the bone, although soft bone, will keep the stool more solid. Only raw wings though not cooked as they are then two brittle and could cause damage x
I did give him a chicken wing one day... I wasnt sure about what else to feed him during that day tho ! whether that's was his total days food or just 1 meal He loved it (of course) but it didn't help his tummy.
I now almost have things stable and have him on some good doggy kibble, so fingers crossed !