Well, L&P has built in a good wife path from the beginning, and given Liam both workmates and an opponent in the form of Carl. In the end, Liam even has his own gangster in the game, much like Dylan has Aiden.
It is important to recognize, however, that unlike Ellie and Dylan, Liam never really resonated well with the players. His story is probably too simple for many. Nevertheless, you can see that Liam was planned to be one of the main characters. He even had an event that was told from his perspective, just like we see with Dylan a few times.
Again, it's important not to try to do everything in just a single game, otherwise nothing will really work. You can really see how AWAM suffers from too many side stories. It would be better if L&P concentrated more on the main stories and made real progress here. Here, characters like Dylan and Ellie are especially important, but also their surroundings, such as Sam, play an important role.