I'll talk OOC first to eliminate confusion. That was a swoop attack - they "charged" in a flying dive, did one attack (vice their normal three) and kept going to circle again. Their intent is to force morale checks on the mounts, not double damage. So, Markd doesn't need to change-up to Melee because it snapped at him and kept moving. Their charge is at a speed of 360' which means they begin the round out of bow range and you get a shot as they close on you. It also means you get a shot on the next round as they depart, because it takes another round to get out or range and wheel around for their next attack. I'm going to count Markd and Halfpint's attacks both as bow attacks and assume you concentrate fire at the one carrying Florin (and the NPCs will shoot, too). I will also count a -2 AC penalty for the one carrying Florin as he lacks his normal agility. Bremen needs a round to reload, so he doesn't get the second shot. If the Hippogriff gets sufficiently wounded, Irving can catch up - otherwise it is 3x his speed. The reins on the mounts were held by the hired retainers who are there to guard them - PCs don't need to worry about leading the mule while paying those guys. 
I discounted the melee attacks against the flying charge, but since it was close enough to grab Florin, Keehnelf has a point (except he missed). I will back-track a melee attack for Florin as he got grabbed, too.
Florin grabs at his mace as the hippogriff grabs at him, flailing ineffectually as he is gripped and torn from the ground skyward. He continues to yell rather undignified things as the beast carries him, thunking it on its feathered chest from his awkward dangling angle with little effect
(-1hp). Irving, dismayed for his clerical charge, begins sprinting after the beast, though its wings promise to be far faster than his legs.
In this time of need, all the archers instinctively concentrate their fire on the one beast carrying their companion. Markd and Guaire's shots go wide, but Bandy
(-3hp) and Neach
(-2hp) both wound the right wing. The beast falters, dropping to the ground; Florin tucks and rolls to freedom, struggling back to his feet. Irving overtakes the beast with his charge, the sheer adrenaline of his rush propelling his blade forcefully into the creature's equine side
(3x2=6hp). In collapses, slain.
Squawks of protest erupt from the other bird-beasts, not yet giving up on what they hoped to be an easy breakfast. They wheel around for their next approach.
Date: 9:15am, 03 June 2021
Light: Sun
Distance: 5.25 miles today
Injuries: Bremen (majorly wounded)Markd (minorly wounded) Florin (minorly wounded)
Rolls:
