Choosing between grand-prey and grand-predator

Considering a 5-player game A > B > C > D > E

Early in the game, C and D have both a vampire, and D can diablerize C's vampire.

A has the final decision about the blood hunt.

1/ if asked before the diablerie, what should be A's decision (or table talk) before the diablerie happens
2/ nonetheless, D diablerizes C. Should A stick to his or her previous decision (whatever it was), or reconsider?

My opinion about the subject, if I were A:
It's not good to have 2 weak grand-prey, grand-predator. I'd rather have one of the two in a strong position, preferably my grand-predator because:
1/ it means that my grand-prey C has to defend himself, presumably against B, my prey. Anything against B is good for me
2/ my grand-predator is strong, with little pressure, and therefore can put pressure on E, my predator, leaving me more space to oust my prey.

Now, if asked before the diablerie, I'd say to D to do as he wants, but in any case I won't burn him because it would mean that both my "allies" would be weakened: my prey can go forward, my predator has no pressure.
And I'd stick to this position because burning the diablerzing vampire would only help my predator (since C loses his vampire anyway).

elotar wrote: You grand prey has to die, but killing him crosstable at the beginning of the game is not my cup of tea.

Maybe, but then you don't decide. You decide only whether your grand-prey burns also a vampire, or not.

elotar wrote: He got vampire in torpor so he is quite weaked already - if you deny diablery than you grand predator will presumably go forward (good) instead of loosing action on it giving your predator free reign(bad).

But by burning your grand-predator's vampire, don't you give "free reign" to your predator for more than one turn?

elotar wrote: If D will diablerise, knowing that you promised to burn him, than in most situations I'll burn him - it may look bad to have two weak crosstable allies, but having strong crostable unresonable player is, imo, much worse.

Is it reasonable to burn a vampire, knowing it won't benefit you? I've never seen truly "unreasonable" players, except one or two, but it's very rare.

Anyway, I'm no big fan of "I do things because I said to, even if it turns out badly for me because of my pride (or whatever)" , but that's only how I see things.