JSWolf:
I would install PRS+ even without second level collection support. At least the new tab-functions (paging with single tab) are worth it. And the CSS-support. And the assignable buttons. And the possibility to hold page content even in standby mode. And the folder browsing function. And the 'last opened books' on the reader-home-page. And the ... ;-)
With a custom build I do have second level collection support (and you could if you invest time to get behind making custom builds). But I do not use it.
For a subcollection 'horror' under 'sereies' you would have to name a new single collection this way:
'SERIES|HORROR'
A.
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