I've cut several of my rare and multi-colored ricordeas into 4 pieces. Once the cylinder shape returns, and its completely healed, a new mouth will eventually form.
I've never had much luck with netting them directly to a rock; although I know many people who have had success with the netting method.
I use a small container, fill it 1/3 of the way with rubble. Fill it with tank water then carefully place the ricordea on top of the rubble. Cover the top with netting, secure it with a rubberband...cutting off the excess netting. (So it won't catch on your rock) Then place the container in your tank where you have low flow.
[note: If your container is full of water and you tilt it slightly as you're placing it in your tank... the ricordeas will stay in place and won't float to the top of the netting.]
I feed directly through the netting and purge the water to assure the uneaten food isn't just sitting in the container.
Hope this helps you.
donna