If you visit the last Nav Beacon multiple times in Heretic, you can spawn repeated Huygens explorers. Not sure why exactly you would want to at this point in the game, as farming them would be pointless, but it can be done.

The Hyper Viper

I personally did not get the part about the Iocrym AI and the sisters because I didn't do the Sisters mission. Maybe Kate could suggest you visit the sisters somewhere in the text briefing after she gets on the Iocrym command center? I think it is indeterminate whether Domina or Oracus sent the play...