How much of a pain would it be to convert a 10 man into a 5 man, but leaving the 10man version intact as an option?

So lets use Karazhan for an option.  Karazhan 10man would remain untouched and operational as normal.  There would be a separate entrance for a 5man version.  It would include everything exactly the same as the 10man, except the stats of the npc's would be halved for 5 people to run it.

Would this require all new database entry's or could the script be copy/pasted and somehow modify the npc's stats within the script?

I don't think you'd be able to too without removing one version of the dungeon.

The only possibility I see is scaling based on how many people in the group when the fight engages.

I was going to basically create a new custom dungeon but using everything inside the current one.  Just trying to figure out the reduction in stats for 5 vs 10 without having to recreate each NPC.

How hard would it be to implement what you mentioned about scaling based on the number of people?

it should be possible, but needs a lot of hacking.

one possability iss to keep the real instance but set only a flag on instance script and change spawns by this flag.

creating a separate instance would be much more complicated but less hacky

Thanks for the info.  I started messing with this and basically have an empty dungeon.  Guess I will work on adding new npc's.  I'd rather it work right then having it possibly bug out.

maybe there is a simple solution.

spawn NPCS twice, once the 10 man spawns and 5 man spawns. then dedect what mode is selected if the first player enters the instance.

then just despawn the 5 or 10 man spawn. this can be done is you make spawns in order.
for example all 10 man spawns have ID < 50000 all 5 man > 50000

just loop all creatures in map (method for this exists or use InstanceScript.OnCreatureCreate to skip the related spawns)