Teresa

Teresa was one of the Nicoli gypsies killed for revenge by a warlock called Cree. Phoebe Halliwell originally went to her to figure out what is wrong with her powers, when somehow Teresa intercepted her premonition. She forced Phoebe to leave and while she was on the phone calling Lydia she was killed by Cree.

Powers & Abilities
As a magical gypsy Teresa had all the basic powers as well as the power of Divination through both Palmistry and Crystallomancy. The first one is revealed when Phoebe comes to her for a reading. Teresa then proceeds to divine what Phoebe's problem is through her hands. From her plams Teresa could tell many things even to the point where she knew Phoebe could see the future. The latter is discovered due to the fact that she had a large crystal ball on her workdesk and her sign outside her shop.

It is unknown if, like Lydia, she had any active magical powers such as telekinesis. Although it is thought not she had one it would probably be a passive one such as Telepathy or Premonition if she did as she did not put up a fight against Cree.

Due to the fact that she was killed by Cree with know she was also a Shuvani as Orin and his son only go ater Shuvanis. This indicates that her magic was very strong indeed.

Romantic & Family Life
Although some fans speculate she was the mother of Lydia it is unknown whther or not Teresa had any family however it is clear that she had no close relation to Lydia or Ava as when Lydia informed Ava about Teresa's murder Ava said "look, I'm sorry your friend was murdered". This indicates that she did not know Teresa nor was she related very closely to her. The same would hence apply to Lydia, being Ava's aunt.

Still, that said, she was one of the Nicoli Gyspy ghosts called upon in the spell used to kill Orin and so must at least have been part of the Nicoli clan.