So, perhaps there is an obvious answer but I don't see it. Chain of Perdition is a force object of medium size... but does it occupy a square? Can allies or enemies move through it? Can you tumble past it with acrobatics or overrun it? Thanks in advance!
Spiritual Ally is a force affect and it calls out occupying a square, so since Chain of Perdition does not, I would say you can occupy the same square it does.