Stop bounty from increasing
So, in your little shack, you have the 3 captives, and Astrid.
You simply walk up to Astrid, give her a love tap (kill her), and walk right out of the shack.
The reason why it's that easy is because of the below:
- The people are blinded by their hoods, and are not classes as "free" NPC's. They are scripted to sit down and not move. You won't get bounty from killing Astrid if their still alive, just as you wouldn't if you kill any of them.
- Astrid is the only "free" NPC that can see you. After killing her, if you got a bounty at all (which you won't), it will immediately disappear as Astrid is the only witness to the crime.
I mean, who would put bounty on your head for killing the leader of the most feared group of Assassins in all of Tamriel?
Stop assaults from increasing
The sad thing is, is that Assaults are as vital of a statistic as Distance Walked. They can't be erased or worked around. (I don't know much about Assaults myself) But judging on everything we have been commenting about, Assaults is more of a "This is how many people you have killed" counter.
I never look at it anyway. You will have to kill people sometime.
As for Astrid's situation, it's up to you. You either kill her, get 1 Assault increment, or kill 1, 2 or 3 of her captives, and get 1 Assault increment each.
As for Grelod, well, as I have stated many times, I believe she is the one worthless, 1 HP woman, who when you kill, has either been scripted to raise nothing (doesn't even give me a bounty when Michelle see's me kill her), or it was your lucky day and you got glitched.