Very cool. Time for mindless speculation!
I would think it's safe to say that the bearded knight is likely the head of the house. We see him a few times. We also see two younger guys with floppy brown hair. I bet that they are the sons and that at least one of them (the guy on the horse) is going to be a POV character. In that same picture (him on the horse), you can see the knight and a younger woman with light brown hair seeing him off. I wonder if she's going to be a sister. There's also the close up of the woman with similar coloring but a slightly different hairstyle sitting in front of a house standard (purple with a tree and sword). Is that crest from a known house or is that going to be House Forrester's crest? If it's the latter, then I would suspect that she's going to be the matriarch of the family and wife of the knight.
So, going off of a very quick and totally speculative look at those pictures, my predication is:
Father - Knight with beard
Mother - Lady in front of the purple standard
Eldest son - Guy on the horse
Younger son - Other floppy haired young brunette guy
Daughter - Gal seeing the eldest son off
I'm not suspecting that they will all be POV characters though. Maybe only one or two of them. The rest will either be other relations or servants, I suspect.
Also, if the House is going to be in danger at some point, I suspect that the bearded knight won't make it beyond the first or second episode. Otherwise, traditionally, he'd be the one that the story would focus around.
End speculation that is likely very, very wrong.