Back in Proe2001 there was a very nice feature in assembly mode: When adding a component you could put a filter on the target by a simple click, i.e. the component of the assembly the new component should use as reference. So, all the other components couldn't be refered to and their datum planes weren't shown.
Assembling was quick an easy.
Somewhere in the Wildfire versions this feature died, unfortunately, and it didn't show up in creo either. Ever since, assembling a component in a large assembly using datum planes is an imposition.
Please let us have this smart and quick filter again.