Monster drop

Well I am trying to make a specific monster drop a certain item. I've been trying to do this for awhile and idk how to. Can anyone help please? Like I'm trying to add these skins I added to drop from low levels so people can farm them and they only seem to drop from either Karen or Helga. Do they only drop from world bosses? Not sure.

In the server files the drop tables.

How do I add them?

To add them you just copy an existing line and edit it to fit your needs.