Familiar stacking lrestriction?

Dealymaniac

when I search whether familiar potental stack, Nexon confirmed it as yes
https://maplestory.nexon.net/news/57190/update-apr-17-familiar-revamp-details
A: Yes, you can summon the same Familiar up to 3 times and the Potentials will stack, unless the Potential bonuses reach their stack restrictions.

does anyone know what is the stack restrictions are? I couldn't find it anywhere
also, does 3 different familiar stack their potential too?

how does the stacking calculate? like 60% drop + 60% drop = 120%? or it is calculate similar to IED formula?

Rexaar

All variation of familiar drop rate and meso drop rate that appear as a buff in the top right corner
(Increases Meso Drop Rate by a small amount
Increases Meso Drop Rate
Increases Meso Drop Rate by a large amount
Increases Item Drop Rate by a small amount
Increases Item Drop Rate
Increases Item Drop Rate by a large amount
Increases Item and Meso Drop Rate by a small amount
Increases Item and Meso Drop Rate
Increases Item and Meso Drop Rate by a large amount)

are treated as unstackable buff (cannot stack with any other version unstackable drop rate/meso buff) (There exist certain drop rate coupon that are coded differently such as legion luck lv1/2/3 that will stack with familiar drop rate buff, but any other one need to be tested on a case by case basis)
Only the highest amount is applied if you have multiple item/meso drop rate familiar potential. (even if the buff icon show all the meso/item drop rate buffs through a specific order, only the highest amount is applied)

Item Acquisition Rate: +10/12% can be stacked infinitely (well 6 times) because it is a copy of the equipment potential version (not affected by the +200% equipment potential drop rate cap)

In general, any familiar potential that appear as a buff in the top right corner is unstackable with any version of itself or any unstackable buff.