I don't have the faiths and pantheons book and I can't seem to find this discussed anywhere on the internet so what are the FR rules or EFU rules regarding Paladins of Hoar multiclassing?

Hoarite paladins may not multiclass in canon.

Which is to say, no Orders for Paladins of Hoar support multi-classes. It's the order that begets the perk, not the Deity,