Oh my Desna, Neil! I could never have imagined that someone would respond so fast, even less you! Thank you so much!
Storywise, the second option is maybe the more "in-character" solution... but the spawns are not really a threat for the party, while Luvick's wrath is something they fear deeply...
The first option, on the other hand, is strictly simpler, and is likely the best way to not worse further the relationship with Luvick and the Vampire Underground (I don't want to punish too harshly my players after a tactical reatreat).
I'll have to think about it, maybe a little mix of both of your ideas could work perfectly for me...
Thank you again for the support!