Let me comment on the mechanics part: Right, there is no equivalent of TFM_AVA in BY_Trans file. I would recommend using NCAP_BND(r,p,FX,yr=0)=2 (via an INS table in BY_Trans) for the r-p you want to disallow. EDIT: Note that Antti has proposed a better solution below.
Generally, regions within one super-region are expected to have very similar RES structures. So, if you want to disable only a few r-p combinations, it is OK. But if there are too many cases, then you probably need to revisit the super-region definition.
Related information: Note that a big difference between BY templates and SubRES files is that the BY recognize regions while the SubRES file is completely unaware of regions. Regions are introduced into SubRES only via their respective Trans files.
Generally, regions within one super-region are expected to have very similar RES structures. So, if you want to disable only a few r-p combinations, it is OK. But if there are too many cases, then you probably need to revisit the super-region definition.
Related information: Note that a big difference between BY templates and SubRES files is that the BY recognize regions while the SubRES file is completely unaware of regions. Regions are introduced into SubRES only via their respective Trans files.