I thought Patrick Wilson & Vera Farmiga's characters are leading couple of the film. However, their characters are more like supporting characters, who appear mostly in the second half of the film.

While Janet is truly center of the film.

In the original 2013 film, Patrick Wilson & Vera Farmiga's characters are more like supporting roles at well??????

Ed & Lorraine weren't much involved in this case, so there was really no story to tell for them. Allegedly, they showed up in London uninvited and offered nothing but shady attitudes about making money off their case. So the movie pretty much makes up / dramatizes their involvement.

Edit:
Here's more appropriate place to discuss this.

Yes I agree. Just watched it and Janet clearly stood out as the main character
Such a gifted young actress