How did you come up with the idea of Silveny? I've never heard of a "horse/unicorn/pegasus" before:)
Honestly, it started with me asking myself, "how do you make a unicorn even more awesome?" And the answer I came up with is: "You give it wings and let it fly!"
Then I googled flying unicorns and found out that they did actually exist in certain stories and that they were sometimes called alicorns. So apparently I'm not the only one who wanted her unicorn to fly. :)