I built a creature with 16 limbs and a focus on grappling. However I could not find any bonus to grapple for having extra limbs. Searching online I found a few forum posts but they seemed primarily opinion based with no sources backing them.
From what I can tell having multiple arms grants NO bonuses to grapple at all. This seems like an oversight as it should be obvious that a creature with many limbs should be able to grapple with bonuses.
What are the bonuses to use the grapple maneuver for a creature having multiple arms? Please include sources.
If there are no bonuses is there a common house rule adding a bonus?