Can I edit/import .drl files?

I found a lot of (very old) posts saying that I can't... but now we're on allegro 17.4. Is it still not possible?

Background / why do I want to do this:

We have a design that is spread over 2 boards. We'd like to try getting it printed with Digikey Red, but their system won't allow multi-board jobs (I guess it's automated? In any case they reject it). So I'd like to "chop up" the fab files such that I have 2 sets of art files and drl files - one for each board. It seems like this should be "easy". Fab houses do this sort of thing all the time, for example to panelize.

Trying to delete things in a copy of the complete design file seems to be a black-hole of problems - maybe it wasn't the "right" way to do it, but I've got the keepins/outs defined as part of a mechanical symbol that is *both* boards together (they fit in the same enclosure, and would always be used as a pair). Now this effectively prevents that avenue. Possibly I could create new symbols for each board, but I'm starting to worry about all the DRCs that I'm going to have to ignore and worried about mistakes when the dynamic copper kicks in.

So I start a new project and import each art file into appropriate layers. This seems to work great - there's no components and the dynamic copper, traces, everything are just shapes I can do whatever I want with and I don't need to worry about anything changing in strange ways. But I can't seem to get the .drl file into allegro in order to do the same for the holes.

Is it possible to import .drl files? If not, any suggestions on the best way to solve this problem?

Thanks!