mtree spec

[Fbsd8]

I have this mtree specification file

/set type=dir uname=root gname=wheel
.
etc
..
root
..
usr
local
etc
..
..
..
..

But I want to have it behave a little differently.
What I am after is etc has to be present and any sub-directories off of 
etc is not a error. Same thing for for root and usr/local/etc

Can I do it using the nlink option on the etc level above or use some 
flag on mtree -d command I feed the above specification file to?