is there a way to add anuther grenade type so like i can have a frag and a plasma and a shield grenade (and im not asking how to swap the nades out) i want a new nade... but in hek it doesnt allow you to make a new one. can someone please help

Halo can't have 3 swappable grenades, you can only have two and then to have the third, you have to make it the secondary fire/trigger of another gun. I don't know how to do it, so just wait for someone else to tell you, unless you already know.

your 2 options are to swap, or add it to the weapon as a secondary fire (meaning the weapon that has the 3rd grenade type cant fire the first 2)

most of tags have settings for 4 nades, but globals.globals, the core of the grenade system, wont let more than 2

so is there anyone that can point me to a tut for a secondary trigger?

look at any vehicle tag with secondary fire. banshee, tank, bulldog...