It's interesting what you miss if you're hollow. I found out that Witch Beatrice was available to summon before fighting the Moonlight Butterfly but only if you reverse hollowing. I also read that she can be summoned again - and does huge damage - for the 4 Kings. But the article said her sign shows up if you summoned her for the butterfly.
Is there any way of summoning her if you haven't done it at the Moon Butterfly? Or am I past the point of no return?