I have the following scenario planned: The PCs are traversing an overgrown swamp that's home to a pair of Gryphs and loads of creepy-crawleys. The specific vermin the PCs are to encounter first will be Giant Ticks.
Now flavour-wise Gryphs have a history of consorting with vermin. And in this case, since the Gryphs' MO is to implant their eggs into helpless targets or targets they're grappling and the ticks have the grab ability as well, I thought the pairing to be only fitting. You know: humanoids get sprung upon and grappled by icky ticks, gryphs swoop in to take advantage and Implant their eggs.
But how to do that in combat terms? Usually the rules for multiple creatures grappling state:
Multiple creatures can attempt to grapple one target. The creature that first initiates the grapple is the only one that makes a check, with a +2 bonus for each creature that assists in the grapple (using the Aid Another action). Multiple creatures can also assist another creature in breaking free from a grapple, with each creature that assists (using the Aid Another action) granting a +2 bonus on the grappled creature’s combat maneuver check.
So I guess when a giant tentacle of unknown origin grapples my party member and starts to pull him towards the edge, I can run up as soon as I find time, wrap my arms around that friend and try to aid him (read: roll d20+CMB against DC10 to give him +2 on his CMB) in wrestling free from the beast.
But can the Gryph swoop in on a PC grappled by a tick and become the grappler (like reversing a grapple) even though it's late to the party? Assuming the tick knows him to be somewhat of an ally, does it give him the +2 through Aid Another and the PC the DEX-malus to CMD through the grappled condition?