Perhaps their main function is to physically enact the agenda of the Parent which follows the plan of the Parents Group.
As example: A Coven member would play the 'god' of a certain religion to cement their following. In more modern times, they like to play the role of ETs or 'higher dimensional beings' for channellers and contactees.
They are above the Bloodlines but for the most part influence the programs and projects more so than the Bloodline Members (aside from the Family Master of course). Some areas they influence the most are religions, secret programs (space, military and science) and the high level cults.
They are responsible for what we call Vampires, Werewolves, Monsters, Spirits, many haunting types, demons, some forms of ET and many other stories of strange creatures or beings. They also do a lot of containment and compartmentalization work 'rewriting' history and recorded events. (Most of this duty belongs to another group however)
These beings enjoy their job except for the rare exception. Very few Coven members have a high opinion of humans and believe themselves Superior to humanity. Something the Parent instills and reinforces within them. This seems to spiritually cripple them causing them to remain stagnant which increases their poor behaviors. They are always causing trouble in the world of humans.
Black Ops/Military, Mind Control technology, Cloning, Space Programs and work in Genetics is all under their care and control as they work on behalf of The Parents. They also work closely with Draco and other ETs for this purpose.
On several occasions they have altered the course of human development by posing as 'gods' or ETs.. Delivered indoctrination through channels and leaders. They are quite clever and inventive groups and share the Draconian ability and lust for deception.
Some of the Covens have become so powerful and corrupt that their Parents lost control and had to destroy their own coven.
Cults tend to knowingly or unknowingly worship them and several well known deities and characters throughout human history have been Coven members before or after they became well known.
They also create the many Secret Societies and provide their doctrine or rituals.
As your writer has mentioned before, one member of each coven become the Family Master who gives orders to the Bloodline they represent. They oversee all of the Systems of Control on this planet. They are however, following orders themselves.
The remaining members of each Coven either fulfill a role or simply exist. Some inspire, some inflict harm, some do nothing besides pursuit self interests.
If the Illuminati were a company, The Covens would be the upper management staff. The Parents, Board of Directors and the Draco the owners or shareholders.
As things are changing, their roles are expanding and some are currently pushing their own projects very hard to maintain control in this critical time. These beings do not work for the planet, or the humans on it, or even the Draco directly. Everything they do, they are either instructed to do, or choose to do so in hopes of pleasing the Parents.
They perform all sorts of nefarious actions in our world and almost all view humans, not as children, but as animals. Their ideology is the commonly known Illuminati ideology as they pass this down to the Bloodlines.
Your writer is choosing not to get into specifics as he only wishes for you to understand the structure for now and how these moving parts work in unison. He believes this is important for you to understand as this pattern is reflected from top to bottom of the Illuminati structure. The Covens have many many attached stories some of which are mentioned above, which could invite further detail, but we shall revisit these another time.
(In the next "Structure" post) We will discuss Bloodlines next which is an area that is more well known to most who seek this information.
We will (writer and readers combined) summarize all of this at another time.