I import my phone apps' backups to a subdirectory via an ADB special remote and importtree=yes but every time I run a sync, it tries to copy files to it that are below numcopies; even those outside the relevant sub-directory.

How can I make it so that it never tries to copy any files to it? exporttree=no, it will provably never work.

Note that you can't make it want nothing because that also prevents import from working.