[Seerah]

You can't do this in each panel though. You can only register an event once. Unless that was just a restriction of eePanels (or it has changed since kgPanels was first released...) In the kgPanels in-game FAQ is a way to get a reference to a panel so you can call multiple panels from one script. I think it's

kgPanels:Fetch("the name you gave the panel when you made it")

So, pick one panel (probably best is the one with a higher panel number) and put the code in there. It'll make it easier to change later anyway, to have it all in one spot...

OnLoad:

 self:RegisterEvent("PLAYER_ENTERING_WORLD")
 self:RegisterEvent("PARTY_MEMBERS_CHANGED")
 self:RegisterEvent("RAID_ROSTER_UPDATE")

local tenman = kgPanels:Fetch("thatpanel'sname")
local twentyfive = kgPanels:Fetch("thatone'sname")

-- Hide panels
tenman:Hide()
twentyfive:Hide()

OnEvent:

local inRaid = UnitInRaid("player")
local inParty = UnitInParty("player")
local tenman = kgPanels:Fetch("thatpanel'sname")
local twentyfive = kgPanels:Fetch("thatone'sname")

if inRaid and GetNumRaidMembers() < 11 then
      tenman:Show()
      twentyfive:Hide()
   -- in 10 man raid
elseif inRaid and GetNumRaidMembers() > 10 then
      tenman:Hide()
      twentyfive:Show()
   -- in 20 man raid
elseif inParty and GetNumPartyMembers() > 1 then
      tenman:Hide()
      twentyfive:Hide()
   -- in a 5 man party
end