Dunno about Dinah. Besides being the Green Arrow’s girlfriend, she’s also a superhero and co-conspirator in her own right. So far, the killer seems to be targeting strictly SO’s of the conspirators, (or, more properly, people who were on the satellite the night Dr. Light attacked Sue Dibney- Ralph wasn’t originally part of the conspiracy) rather than the conspirators themselves. His objective seems to be to hurt them, rather than kill them, but that could change.
Possible targets might include Mia Dearden, who isn’t a romantic interest for Green Arrow, but is part of his “family”, and might present a target. Killing her would be a pretty deep cut for both Ollie and Dinah. She’s a tough cookie, though, and would have more than a snowball’s chance of fighting her way out of it. Connor Hawke might also be on the list, though he’d be pretty hard to bring down.
Don’t know much about the romantic/familial connections of Hawkman and Zatanna, but I’m thinking that Hawkgirl ought to have someone watching her back about now.
And if Bruce was on the satellite, targets would include Tim Drake, Selina Kyle, Talia Head, Barbara Gordon, Dick Grayson… basically, any of his ex’s who he still might have feelings for, plus members of the extended Batfamily. I’d bet that if anyone close to Batman was a target, it would come down to either Tim or Babara. Barbara is probably the most vulnerable target in his circle, but since Brad Meltzer et al seem to be keeping Tim in the forefront, I expect an unsuccessful attack on him in the near future.
Family members of Barry and Hal would likely not be targets, being as how they’re both dead, and messing with Hal’s family about now would mean risking bringing the Wrath of God down on one’s head. Wally and Kyle seemed to have stepped into the conspiracy roles as well as the tights of their predecessors, though. I haven’t been following Green Lantern and the Flash, but it would probably be a good idea for them to beef up security around whatever loved ones they may have.
Also, loved ones should be armed with something more than a crossbow, which is an ineffective weapon if 1) you’re not actually carrying it at the moment you are attacked or 2) You can’t fire it backward over your shoulder through a wooden door.