AHA, so I wasn't the only one. I was having a problem where they were "eating" each other. The solution for me was to hard-code those that were immovable and then the movable ones remained movable. There is a sort of solution if you try googling "cannabalism" but another way may be to use layers
I use layers for a grid when I want to place images/sprites, then I delete the grid when finished -=mh=-