Fade out a subset group fades all members of the superset group

[spinnerbox]

I have this code: 

init: function () {

    screenObjects = gameObject.add.group();
    guidesGroup = gameObject.add.group();
            
},

create: function () {

guide1 = gameObject.add.sprite(0, 0, si.ImageAssetKeys.GUIDE_1_IMG);
guide1.name = 'guide1';
screenObjects.add(guide1);
guidesGroup.add(guide1);

guide2 = gameObject.add.sprite(0, 0, si.ImageAssetKeys.GUIDE_2_IMG);
guide2.name = 'guide2';
screenObjects.add(guide2);
guidesGroup.add(guide2);

guide3 = gameObject.add.sprite(0, 0, si.ImageAssetKeys.GUIDE_3_IMG);
guide3.name = 'guide3';
screenObjects.add(guide3);
guidesGroup.add(guide3);

nextButton = si.SIButton.SIButton(360, 670, si.ImageAssetKeys.GUIDE_BUTTONS_SHEET, thisObject, click, 3, 2, 2, 3);
screenObjects.add(nextButton);

prevButton = si.SIButton.SIButton(10, 670, si.ImageAssetKeys.GUIDE_BUTTONS_SHEET, thisObject, click, 1, 0, 0, 1);
screenObjects.add(prevButton);

}

As you can see guides belong to screenObjects and guidesGroup groups, but previousButton and nextButton belong to only screenObjects. I am using this code to fade in/out guides in guidesGroup but the problem is the next and previous buttons are faded out as well.

guidesGroup.forEach(function (item) {
   var siObject = this;

   item.alpha = 0;
   if (item.name === 'guide1') {
        siObject.gameObject.add.tween(item).to({alpha: 1}, si.Const.FADE_DURATION, siObject.Const.TWEEN_LINEAR, true);
   }
}, si);

Is there some mixing between game groups, are they distinct if same object belong to two groups?

[spinnerbox]

Wait, the addition of new objects has effect on what is on top of what?

guidesGroup.add(guide5);
screenObjects.add(guide5);

is different than

screenObjects.add(guide5);
guidesGroup.add(guide5);

With the first one guide5 is below prev and next buttons in screenObjects, in the second, guide5 i above prev and next buttons, so as it fades in buttons fade out  i.e they are below guide5

What are Phaser groups actually, are the separated from each other?

[drhayes]

Is "screenObjects" a group? Display objects in Phaser can only have one parent at a time. If you add a sprite to Group A, then add the sprite to Group B, it will be removed from Group A and will only be in Group B.

This might explain some of the z-order stuff you're seeing that you asked about here: