if I have created an animated character scene and for example wish to set it in the indoor scene that comes with iC5 I have had to save my scene, open that one, add all the props tp the library and then reload them in the first one.

example

I did the litter physics sim first and then wanted to put it in the indoor room.

When you've added Props & Characters, your "Scene" becomes a Project & is Saved as a Project  & not Scene File, although you can subsequently replace the 3D Scene or 2D Background.

Anyone-else?  

many other programs do which helps in building up complex scenes

infact it was the only way I could add 30 or more figures to a Daz studio scene for animation without crashing it.

I also do this regulary in Carrara and Poser.

this would be a good feature to add to iClone, obviously a replace or use existing camera and lights option would be needed as iClone does not appear to support as many additional lights either.

This isn't possible in the current version but I have now added this to the Wishful Features list.

Thank you for the feedback. :)

Yes. First you attach each prop to a parent prop by clicking Pick Parent under Attach (Modify panel) and selecting the parent prop. Once done, click Merge for the parent prop. You'll end up with a single, merged prop.