The sites are all part of
http://wtfbucks.com.
To explain the problem, have a look at
https://www.indexxx.com/models/59558/anjelica-1/
https://wtfpass.com is a network site, but maybe it doesn't give you access to Nudme, a site of WTFBucks. If it would be grouped under "wtfpass.com" network at indexxx and if "wtfpass.com" would be a link, when users would think that joining WTFPass will give you access to Nudme, which may not be the case. So a second parent/network is created at indexxx, named "WTFPass2", which is not linkable, so that users see that there are some sites that are part of WTF, but don't give you access to the WTFPass network.
But I cannot verify the current status of Nudme, so maybe joining WTFPass does give you access to Nudme.
I have just processed your comments, so it's added to indexxx