I could have sworn we had a question on this already, but I can't find it via Google or RPG.SE's search bar.
A little background: EN World's Patreon-supported publication Trailseeker just released a new hybrid class, which is a druidic take on the wizard class. One of its potential focuses is on summon nature's ally, with that path's late-game ability increasing the total number of summoned creatures by one. I know I've seen an ability like that before in a non-3pp product (maybe Advanced Class Guide), so I don't feel this question is third-party specific, but this was the first time I'd seen that ability side-by-side with the Superior Summoning feat (which can be taken by that path as a bonus feat) and I realized...
Superior Summoning increases the number of monsters you get from a summon spell by one, if and only if the spell would already summon more than one monster. There's a related question on the Paizo forums about whether or not Superior Summoning kicks in if you summon monsters from one list lower and roll a 1, but today I'm looking at its synergistic capability with summon-enhancers: If I summon a creature from the top list a spell can access, thus normally summoning only one of that creature, will a class feature that allows me to summon an additional creature ALSO trigger Superior Summoning for a third creature? Or is there some "order of effects" or something else I'm missing?