Oh, Morticia! I've never seen something so concerted and all of mine get cremated and set on the shelf in a box, but even though there is no grave, I have seen mine mourn greatly for their pals. Maybe all the neighbourhood cats knew Pie well and are really grieving? Wish I could have seen that; how touching.

I've seen docu's which show elephants going to their graveyards and grieving, audibly, for their lost ones. Why not our moggies, too? Maybe Pie asked them to as a sort of farewell to you all.