You can find our Collection guidelines in the Contribution Bible. And these specific collections have already been discussed here.

Hi, I have seen the discussion but as Justice League is a sequel of Man of Steel and Superman vs. Batman it belongs in my opinion in the Man of Steel Collection. Even on Google it is displayed as one Series of 3.

I think that the theme of the collections should be reviewed, with the arrival of the universes is obsolete, for example the Avengers trilogy although it is a collection by itself can not be understood if you do not see all the Marvel movies

I'm not sure I understand the issue you're raising @AbejoSid. Collections and Universes serves different purposes. They're complementary features.

The DC or Marvell films are correlative, and many of them are supported by previous films. In the case of Batman v Superman, it is the sequel to Man of Steel, and the prequel to the Justice League, in the same title as the movie says ... (Batman v Superman: Dawn of Justice)