So, Frank does a good job of filling Lilly's hole? Yes, I think she'd agree!
I would say that she is definitely satisfied. At least Frank has never had any complaints about this.
A little anecdote: A few days or weeks before the update, I had wondered "What happened to the siblings Frank met back then and initially thought were a couple?" and then the sister actually appears in this update.
What was going through my mind yesterday: Each of the sisters will have their own story, apart from the main story. The order is Lilly, Abby, and Becca.
The first part of the plot was pretty much the Lilly plotline until Lilith's longing, we learn more about her problems and every now and then we had Abby plotlines that allow for later things in Abby's plot (Abby's birth father, story around her mother) but also move Lilly's plot forward (when Abby was upset Lilly herself, who wasn't quite on his good side at the time, admitted that even she couldn't blame him for it) and the line "You're as much a daughter to me as Abby is to me" has a weight to it that's impossible to deny.
Currently, we're primarily in the Abby storyline now, with the confrontation with her father, Abby becoming more confident and not taking any more shit from Shannon, and secondarily Lilly and her healing process taking very big steps (from "I don't trust you with Abby" to "I don't trust Abby with you") and I would also argue that she's also very slowly opening up to the idea of Abby and Frank.
It may be a long road, depending on how it's handled, but there's definitely movement from "if you touch her I'll castrate you" to the mutual teasing that they do now (like Frank joking about Abby and Lilly getting married and Abby being surprised that Lilly gets pregnant and the kids look like Frank). I could well imagine that there will be a big jump in the next update. But if there is, it will depend on whether CNG releases Abby's story by then. Before then, I think definitely not.
That leaves the final chapter: Becca. Abby and Lilly have had a big conflict to overcome so far, which was dramatic for them both in the beginning (because it made sense narratively). Now what, if any, could be the big conflict with Becca? It would definitely have to be something that she doesn't see coming and that kind of pulls the rug out from under her. The general plot line, so far, is obvious, at least in theory: all her machinations behind the scenes, like how Lilly's ex-boyfriend lost his job.