Tetrasia was able to feel a certain close connection with Zeta from the very beginning. That was also one of the reasons why her guard was down throughout the whole interaction. This close connection was something that all the creations of the will of the universe had among each other.
Zeta had now evolved past having any connection with the universe and if she wanted, she could have easily cut that connection off.
But for Zeta, her origin was a very important thing to her and she also had no bad feelings toward her mother, the will of the universe for trapping her inside the garden of Eden for so long.
That was why Zeta had still maintained the close connection with her mother and that was also the reason why Tetrasia was able to identify Zeta as a kin.
As for Elena, she had supplied her with universal origin energy. That was something extremely rare and valuable. Without having permission from the will of the world itself, no one would be able to manipulate it.
