could you not use a global var.
something like system; every x sec's set global var to (1). . . . .
compare global var = (1) create object tiledbackground at x.x.x
= (2) create object (different) tiledbackground at x.x.x
you would need to load all backgrounds into layout then use "not on screen" to destroy ones not yet being used.
and dont forget to destroy the replaced one.