I just got done rewatching the pilot and I am so confused now.

The circle is suppose to consist of a child from each of the 6 families, resulting in 6 children making a complete circle.

Now since Cassie and Diana are both Blackwells and there is now no Meade in the circle how did the circle get bounded?

I also want to know if it's only one child from each family how is it that Jake could take Nick's place?

Also I noticed Charles using magic to kill Cassie's mother. I thought he along with Dawn were powerless.?

Oh and how is it that the circles parents were all in the circle= 12 people.

It's mentioned Thayer Diana found her mothers Journal but her dad was also in the circle as a witch.

Faye's mom

Adams dad

Cassie's dad and apparently Diana's

Melissas dad or mom

Nick or jakes dad or mom

That's like 7-8 people counted right there and Diana isn't even Charles's daughter.

The number of parents is really confusing and i dont understand it either it does not make sense unless diana father had a brother or sister that is the parent of an individual in the circle. Also John Blackwell is not part of the circle is a outside witch. So Diana is presenting her mother heritage while someone else in the group is representing her "fathers" heritage. There are too many parents for all of them to be witches from separate families therefore there has to be siblings like jack and nick.

Also charles used a crystal to kil Cassies mom you see that in the pilot he has the crystal in his hand. And we know that melissa's mom was a witch from something John Blackwell said but we are not sure about her father.

i have the same questions... specially about the parents.. (we also know faye´s had magic because we met faye´s grandfather from his father side and he had magic so... it´s only logical.. )

Well, I think as far as the circle members go, they need at least 6 to be bound. Therefore, the parents could have been a bound circle with more than 6 members. I'm not sure if that's fact for the show. It's just a guess.
I'm guessing also that since Diana and Cassie have different mothers, they can have places in the circle.
Jake and Nick have the same parents. Apparently, when Nick was bound to the circle, his bloodline was bound to it. So when he died, Jake was able to "fill his spot" because he was the same bloodline. This probably only works with siblings because they're the same generation. Although, going along with the idea that you need at least 6 or more witches to bind the circle, siblings may have to be in the same circle then. Perhaps, Jake was bound into the circle when Nick was. He just didn't have to be there.
And, yep, as ScFc001 said, Charles used a crystal to kill Cassie's mom.
Hope this helps!

i know , no meade = no bonded circle god the writters are dumb sometimes they cant even follow what they right this confuses me as well