@Paul Raven I was thinking of exactly the same examples when I saw the title of the thread. The Frames became a core family and were represented through Frankie and Sharlene until the end of the show. Clarice is such an interesting case because she came on the scene as a supporting character, but wound up having not only her family (the Hobsons) but also her husband's family (the Ewings) built around her. It could be argued that at one period in the late 1970's to the early 1980's from her involvement in plots with Ada, Iris, Cecile, and Sally, she was the central hub of the show.
I co-nominate Hope Williams (DAYS) and Laura Spencer (GH). Both women were wild teens. Laura was overwrought with emotion, she would have fainting spells when she found out that Leslie was her mother, and eventually she shot her mother's lover. Hope was kissing older boys, she was horrible to Julie, and she had to be sent to boarding school because she was getting into so much trouble at home. However, once they started dating the local bad boys in town (Luke and Bo respectively), they became damsels in distress, always in need of being saved from criminals, and frightened by the mere thought that their boyfriends would be exposed to danger. It got to the point where these two tough teens both began to be referred to as "princess" by the beaus. Although they both had a brief resurgence in the 90's when they founded their respective cosmetics companies, eventually they both subverted everything they always wanted as kids and became a sidekick to men who weren't nearly as complex or interesting, and would eventually abandon them. If 15-year-old Hope or Laura were able to predict the future and see what their lives would be like living in tiny homes in the same town that they were raised, I bet both of them would have gagged.