Objects in linked scene don't have group memberships?

I’ve linked to a (background) scene and correctly see all of the objects in that scene … including a certain tree.

The tree, in the original scene-file, is part of a “TreeGroup.” And, all of the “leaves” of that tree are children of the tree trunk.

When I look at the same scene in the file that links to this one, however, the Tree has no group-membership at all. And, neither do any of the leaves. There they are, and they’re shown as children of the Tree object, but the group-names are all gone.

Furthermore, if I Copy Selected to Scene … only the Tree object gets copied; none of its children (the leaves).

The Tree is “part of” the Scene and I want to treat it that way in all directly or indirectly-linked scenes. (Blend-files which use a set, link to it, and every camera-position is in other scenes within the same file, which all link to that one.) What’s the best linking strategy, between the scenes in the file, that will do that?

Well, here’s what I’m trying and it seems to work well enough … comments, please …

I moved each of these things (flowerpots, houses, trees) into a normally-hidden layer. I reset the origins for DupliGroups “to cursor” using the button provided.

Then, everywhere those objects are to appear, even if they appear only once, I added a Group Instance to the visible layer. I basically ignore that the “members of the group” object exist.

So, in effect, this hidden-layer is acting as a sort of library of assets, “within the same file,” acting functionally much as would be the case if linking to assets between two files.