you *could* make that happen easily.
There is the base root volume in cDOT (/) where all
junctions usually form.
You would have to set the export-policy on the root volume
to something that is writeable by a client.
Mount the root of the cdot filer and create the EMPTY
volume call vol. That is your place holder.
Then, when "mounting" a junction in cdot, do something
like:
vol mount -volume share_01 -junction-path /vol/share_01
and it should work. I did this in a past job with hundreds
of volumes so I can tell you it works.
You just need to make sure your export-policies are set the
way you want/need and be sure to limit the root volume
export-policy when you are done.