Try All Bran or Bran Buds.
After gall bladder surgery, my poop was very greasy and required a mile of toilet paper to clean it up. Someone online recommended Bran Buds.
I started having a 1/2 cup or more each morning. You can eat it with milk, but I crunch them down dry and drink something with them.
I am happy to say that my poop came on a regular basis, lost its greasy-ness, and it was very bulky, which is good.