I've never understood this. "My Aeducan obviously put Harrowmont on the throne, Bhelen betrayed me!!".
To Dwarves their clan and heritage is everything, they take far more pride not in themselves, but in the standing of their families. A Dwarven noble would always prefer to place a member of their family on a powerful position because they are not looking out for themselves, their personal issues and arguments are second to their families standing. In fact, as opposed to being shocked and feeling betrayed, it would be far more in line with Dwarven culture to respect Bhelen more after such an act of betrayal because he outplayed and beat you at the game. It is actually quite similar to the Orlesian "game".
Any Dwarven noble should be trying to get themselves on the throne, if this is not possible and the noble is disqualified for reasons, like being a Grey Warden, they would settle for the next bet thing, getting another of their clan on the throne to continue the legacy of their bloodline.
Any Aeducan Warden who put Harrowmont on the throne due to Bhelen betraying them was being played by a person who gave their Dwarven Warden a human mindset.
First, that isn't exactly what I said. Everyone has their own take on this, but frankly, if there was only one true way for an Orzammar dwarf to think, what would be the point of giving people a choice?
I was talking from the perspective of that particular Aeducan warden and the personality I gave her, who is someone who puts Orzammar above even family (she has the Paragon Aeducan thing going, go read the codex stuff for the founding paragon if that doesn't make sense). And since their father supposedly supported Harrowmont over Bhelen, I think the standing of family isn't more important than anything else even generally. Being convicted of being a kinslayer, at any rate, is probably good grounds for holding a grudge stronger than family loyalty (I find the dwarves far more complex as individuals than just "family first and everything else can go to h**l.) I actually read them as putting personal interest ahead of family a lot of the time, myself. Big talk about honor in public, but that's not what plays behind the scenes.
That said, my second dwarf, with a different personality and more suspicious of Harrowmont, will let his suspicions tilt the balance toward Bhelen instead.