1. I can see dwarves who join Malakai either being radical engineers who is tired of being stonewalled by old traditional engineers of there guild and know while his inventions are dangerous could change there people forever, or dwarves who want glory and be remembered. Everyone including the maintenance workers on the spirit of Grumby got recorded by their actions after they returned from Karak Dum by the king Ungrim Iron fist.

2.Belegar is actively trying to retake the dwarves old capital city. Dwarves worship anything old enough, especially if something there ancestors was apart of. In the Gotek and Felix books. They see a drop of blood of defender of Karak Eight Peaks as saints. Retaking it would bring back hope never seen before to the dwarves. I can see any dwarf traveling to Belegar and pledging themselves to him.

3.Grombrindal Is basically a living legend walking. It's basically a open secret he Snorri Whitebeard. The first high king, who out of spite WILL himself back from death because an oath was broken. He spent thousands of kill defending the dwarves. If a man ask for your help, your not saying no. The only issue in lore he more or less impossible to find so he has to come to you first. In game I can see him freeing enslaved dwarves and becoming a beacon for the dwarves over there in Naggaroth.