How to adjust Weapon dmg in Archetype

[Thorneldrich]

Ok I am attempting to create a Fighter Archetype who is basically a weapon master of dual-wielding whips. Gotten most the stuff done but running into a problem as follows:

At set levels (4th, 8th, 12th, 16th, & 20th) the damage the the Archetype inflicts with a whip increases one die step (1d3 to 1d4 to 1d6, etc...). I can't seem to figure out how to code it into the archetype (tried looking at the Monk but couldn't find the code for his unarmed die increase/set levels).

Also, I am not sure how to set his Chosen Weapon as whip automatically (currently I just use the Weapon Master's Chosen Weapon & pick "Whip").

Any help would be greatly appreciated. My workaround at the moment is clumsy at best (basically have to use personal adjustment tab & use Weapon Die Step to manually set it up at each archetype level-point for each whip).