Amy-- was a high school student the last time she was seen. She had a strong crush on David Banning and babysat for Scotty. Amy was the youngest Kositchek child.
Jake-- was in love with, and engaged to marry Jessica Blake. They seriously dated for about a year. When Jessica started flipping into her Angel personality, Jake lost it and started strangling women. As the Salem Strangler, he attacked Denise Peterson, Laurie Masters, Samantha Evans, and Mary Anderson. Jake was the middle child in the family.
Chris--was the family member who spent a lengthy time in Salem. He had many loves in Salem, but was never married. He was engaged to Kayla Brady at one time. He also dated Mary Anderson, Leslie James, and his law rival and partner, Leslie Landman. In the mid-80s, he became the owner of Shenanigans, a small burger restaurant in Salem. In 1987, Chris disappeared from the show, but he could very well still be living in Salem.
Stan-- worked for Anderson Manufacturing. It was because of his years of loyal service that Bob Anderson gave Chris a scholarship for college. Stan raped a girl named Cathy Breton, whom the Hortons were very fond of. She got pregnant after this and left town. So presumably, somewhere, there is another Kositchek floating around.