Nope. The rules do not address doing that, so it falls squarely in the category of GM adjudication whether it should be possible, and what the details of attempting it would be.
It'd make a fine enough feat or houserule....
houserule, not a real rule
If the grenade lands in a square or at an intersection of a square within your natural reach, you can use a reaction to make a reflex save (DC equal to the attack roll of the grenade throw) to throw the grenade
Sounds fun and all, but I can't imagine that players would appreciate NPCs throwing back their own grenades that costed the players way more money than they're really worth. If anything I would make it a feat or cost a point of resolve, so NPCs generally won't have access to that ability.
I like the resolve point idea, but I don't want to hijack this thread.
If you want to make a post in the homebrew section, we can further refine the idea.
I like the resolve point idea, but I don't want to hijack this thread.
If you want to make a post in the homebrew section, we can further refine the idea.
There really isn't much else to this thread, anyway, since the question already got answered. It sort of already is a homebrew topic starting from the third post.
While I don't plan on making a thread about it, since I don't know where I would start, but I definitely will give my 2 cents if someone else does or discusses it here.