Generally the show would focus on Lucinda reacting to another relative, usually one who was long-lost, if the story wasn't about Lily. Marland returned to the pattern previously established with Sierra by bringing in Neal and Royce. Then after Marland's death, Sam filled that void. Then as Lily moved into a more settled life, they brought in he's-her-son-oh-wait-he-isn't David, and granddaughter Georgia, along with the bizarre James romance. I don't think any of this ever would have lasted, to put it kindly, but Liz Hubbard's hostile relationship with Felicia Minei Behr ensured it wouldn't. Then, when Liz returned to the show, she was mostly kept in an even stricter supporting role, there to react to Lily or to Craig.
I do think Lucinda's use in the last year, so heavily manipulating various story strands and finally leaving for a life of her own after Lily took Worldwide away from her, was satisfyingly done - more than I would have expected by that point, anyway.