How does hybridizing occults work?

I've made hybrid sims many times.  I use the following cheat codes for my hybrids:

Vampires  Traits.Equip_Trait Trait_OccultVampire                                                                                                                                                                  Stats.Set_Stat RankedStatistic_Occult_VampireXP 1593

To give the sim either the Mist or Bat Powers that will work after the removal of the Vampire Trait.  PS: Repeat Power Code as necessary.

Spellcasters  Traits.Equip_Trait Trait_Occult_WitchOccult                                                                                                                                                      Stats.Set_Stat RankedStatistic_WitchOccult_WitchXP 2350                                                                                                                        Stats.Set_Stat RankedStatistic_WitchOccult_WitchXP 2850 

The Magic will linger a bit even after the removal of the Spellcaster Trait. 

Werewolves   Traits.Equip_Trait Trait_OccultWerewolf                                                                                                                                                                 Stats.Set_Stat RankedStatistic_Werewolf_Progression 3000

To give the sim the Werewolf Speed, Howls, Healing & Immortal Powers that can work after the removal of the Werewolf Trait.  PS: Before removing the trait, remove the negative temperaments.

These are my suggestions as I'm only a vanilla player on my PC; I don't use any mods, mccs or ccs.  I depend on only my Sims 4 Pack Cheat Codes & they so work.  Also, I advise do not have other Occult Traits on when having Werewolves at the same time, the sims will either look weird or become invisible, I learned that the hard way.  That being said, Spellcasters works wonderful with Vampires at the same time or Spellcasters with Mermaids at the same time or even Spellcasters with Aliens.  Yup, I've used them all.  Now, if we only were giving actual Fairy Occults.           

The usual way is this: babies born have 50% to be one parent's occult status and 50% to be the other parent's occult status.

Here, the babies would either be born as a werewolf or as a spellcaster. Both occult statuses will be impossible (unless there's a coding error like with Dormant Werewolves), so either this or that.

However, two things to remember:

1. Because one of the parents is a spellcaster, the children will get a stronger magical bloodline trait.
2. Werewolf babies have a chance to be born as a Dormant Werewolves. In case of two werewolves, it would mean that the baby will be a human sim with Dormant Wolf trait. Not sure about the other occults.

The Dormant Wolf fact could be used to make a spellcaster-werewolf hybrid eventually, but it will be buggy as the needs panel will be messed up, it's harder to access each occult's perks, and the werewolf form will be messed up. Here's a post I've made years back on it.

DrearyMaeI've never had a spell caster breed with a werewolf before, but I've had a dormant wolf breed with a vampire and a mermaid breed with a spellcaster. The dormant wolf and vampire had twins: one vampire and one vamwolf. The vamwolf was to all appearances an ordinary werewolf child to begin with, aside from the fact that he was immediately hated by both vampires and werewolves. When he aged up to teen he developed more vampire elements. He had three forms, one human, one vampire and one werewolf. The werewolf form was not editable in CAS, and was badly deformed when he turned into it. The vampire form couldn't be summoned on command. His needs panel had a combination of werewolf and vampire elements that, taken together, were hard to read. Poor kid was cursed. Eventually, he took the vampire cure and was turned into an ordinary werewolf. He married a human and had an ordinary werewolf child. 

The the mermaid and the spellcaster had a merboy with a spellcaster bloodline. I won't call him a mercaster, because he was a typical merboy with no spellcaster abilities. The spellcaster bloodline was just sitting there in his psychology panel doing nothing. It's possible that it gives him the ability to have spellcaster children without a spellcaster partner. He's currently grown up and engaged to a human. I'll let you know what happens if they have a child.

As for triplets, I haven't found occults to be particularly prone to having multis. The dormant wolf in the first couple had the Fertile trait. So you'll have to do something (possibly cheaty?) to make it happen.