I'll be playing a gish with spellcasting based in the sorcerer class, his bloodline is primal elemental and at 9th level I plan on having him take the "Signature mount" third party feat.
Now, what I'm wondering is if the share spells thing will work with my character's companion/spell list. Since the ability in question goes like this:
"Share Spells (Ex)
The druid may cast a spell with a target of “You” on her animal companion (as a touch range spell) instead of on herself. A druid may cast spells on her animal companion even if the spells normally do not affect creatures of the companion's type (animal). Spells cast in this way must come from a class that grants an animal companion. This ability does not allow the animal to share abilities that are not spells, even if they function like spells."
Does that mean that since my character gets his companion via a feat rather than class, he cannot cast spells via this feature? I'm unsure since technically a sorcerer can be a class that grants an animal buddy (sylvan wildblooded) but isn't in the case of my character as his bloodline is a different one.
"third party"
In this case, the feature you have for this mount isn't functional within the rules of Pathfinder. Likely due to it being 3rd party and not having the best writers possible who actually understand the rule implications of whatever madness they're writing. /shrug. It happens.
Luckily, not too many of the animal companion's abilities are nonfunctional because of this basic incompatibility. So, you should be fine.
tldr; No, Share Spells doesn't do anything for you. Not if you don't get your companion from a class...
(The most lax reading you could possibly get is that you can share all of your personal 'druid' spells with this companion. So.. you know, still no help.