Disruptive Companion + Disruptive

[Jinotad]

So, I was wondering how the disruptive feat interacts with itself, and disruptive companion.

Disruptive does not give any bonuses or penalties; rather, it increases the DC of concentration checks to cast defensively. If two characters with this feat were adjacent to a caster casting defensively, would it stack to increase the DC by +8?

Disruptive Companion increases the concentration check DC of spells and spell-like abilities that opponents cast while within the animal companion’s reach by +2. It also allows the animal companion to have Disruptive as well. So, would the two feats stack, making the defensive casting a +6 to the DC?

Disruptive Companion:

Source Ultimate Wilderness pg. 217
The animal’s presence harries nearby enemies, making concentration difficult.

Prerequisites: Animal companion.

Benefit: The animal companion is trained to interfere with its opponent’s concentration, making even rote tasks difficult. Increase the concentration check DC of spells and spell-like abilities that opponents cast while within the animal companion’s reach by +2. Additionally, opponents can’t take 10 on d20 rolls or checks while within the animal companion’s reach. If an opponent has an ability that allows it to always take 10 on certain skill checks while distracted (such as the skill mastery advanced talent), it gains the benefit of such abilities only if its number of skill ranks is at least 4 higher than the animal companion’s Hit Dice.

In addition, the animal companion counts as a fighter with a number of class levels equal to its Hit Dice for the purposes of qualifying for the Disruptive feat, as well as for any feat that lists the Disruptive feat as a prerequisite. The animal companion also adds those feats to the list of animal feats that it can choose from when gaining a new feat.

Disruptive:

Source PRPG Core Rulebook pg. 122 (Amazon)
Your training makes it difficult for enemy spellcasters to safely cast spells near you.

Prerequisites: 6th-level fighter.

Benefit: The DC to cast spells defensively increases by +4 for all enemies that are within your threatened area. This increase to casting spells defensively only applies if you are aware of the enemy's location and are capable of taking an attack of opportunity. If you can only take one attack of opportunity per round and have already used that attack, this increase does not apply.

Stacking:

Stacking refers to the act of adding together bonuses or penalties that apply to one particular check or statistic. Generally speaking, most bonuses of the same type do not stack. Instead, only the highest bonus applies. Most penalties do stack, meaning that their values are added together. Penalties and bonuses generally stack with one another, meaning that the penalties might negate or exceed part or all of the bonuses, and vice versa.

[LordKailas]

since the feat provides an untyped modification that is technically a penalty they probably stack. As for the companion, since there isn't any language stating that it overlaps with the feat, it probably also stacks with the feat.

Unfortunately, I was unable to find anything more definitive than that.

[blahpers]

They definitely stack.

[Old "Scuttlebutt" Salt]

I concur due to the reasoning LordKailas cited - untyped bonuses do stack, and these all appear to be untyped bonuses, therefore they do stack! Happy hunting!