I do not think you necessarily need to take the leather back to the LFS. You just need to provide a physical separation of the anemone from the coral (a.k.a. like option 3, using a flat piece of live rock to make a physical barrier).
The problem with amenones is that they will move until they find a location that best suites their needs (water flow, light, temp, food, etc). I would let the anemone find that location, then relocate any effected corals or provide a physical barrier to protect the coral from the anemone.
I believe you stated the anemone divided? Maybe sell/trade off one of those anemones?
Good Luck!!!
Jeff