There are two examples, I can think of that meet what your last question is looking for. Harinagara and Bindulaa. Although technically they are not mentioned as deities in the religion they are originally mentioned in (as in humans reading). You can tell it is a reference to the four horses of the four horsemen of the apocalypse in Christianity from the mention of Christianity earlier in the story, their colors, and the fact an unnamed avatar of Vishnu is foretold to help the evil Kali (after he gets a boon). It being Harinagara fits nicely with his destructive wake in Christianity.
Soot jee said:-" The dharmic king Deshraaj had worshipped and served lord Sun
about twelve years continuously. After that lord Surya (Sun) got pleased with him
and told him: - "Ask any boon from me”. He said: - "Dev! (Lord!) I bow towards
you, if you want to give me anything as a boon then please provide me the horse
that can fly in the sky." Having accepted his want, he gave him Papihaa (the one
who protects every lokas) named horse. After that, Papihaa named horse, who
protects every lokas, have been stuck by arrow of Madana and cannot control his
sex and begat with Harinee named divine mare. Which cause divine Harinee to
produce pale colored male horse named Manoratha (Manohaaraa) and black
colored male horse named Karaala (frightful). The both came same time from that
single womb and they were part of Shabya (one of the warrior in Mahabharata)
and Sugriva (important character in Ramayana). After that from the part of Jishnu
and Vishnu there took birth two horses from the womb of Harinee. One is
Meghapushpa (divine name), which is golden in color and was named Bindulaa
(Bendulaa) and other is Balahaak (divine name) which is white in color like snow
and was named Harinagara. This were the first four horses produced from the
divine horse Harinee and Papihaa and from those four divine flying horses, many
By the way, all four horses are important to the rest of the main story.