The new frame pool system changed the way party frames work. The existing PartyMemberFrameN globals were removed and instead new unnamed frames are being created.

These aren't unnamed, to me at least - the schema they use is CompactPartyFrameMemberX. I've been updating each release's Blizzard.lua file to this and it's been working fine on beta for me.

I don't yet know what the Pet frames are called, but hopefully I'll get a group with a pet soon.

Yeah, I've been able to make the compact frames work by adding them as @Toludin mentioned:

	table.insert(unitFrames[""], "CompactPartyFrameMember1")
	table.insert(unitFrames[""], "CompactPartyFrameMember2")
	table.insert(unitFrames[""], "CompactPartyFrameMember3")
	table.insert(unitFrames[""], "CompactPartyFrameMember4")
	table.insert(unitFrames[""], "CompactPartyFrameMember5")

Without doing that, and with the below snippet, all the compact frames work except the player's.

For the standard frames, they work if I insert this into RegisterBlizzardUnitFrames:

	for memberFrame in PartyFrame.PartyMemberFramePool:EnumerateActive() do
	    Clicked:RegisterClickCastFrame("", memberFrame)
	end

for memberFrame in PartyFrame.PartyMemberFramePool:EnumerateActive() do
    Clicked:RegisterClickCastFrame("", memberFrame)
end

This did indeed fix it for click-casting but there was a second issue regarding hover-casting, that took some time to resolve.