Kivy. Checkbox on top of background image

Question

My goal is to set the checkbox on top of the image in below class. I'm struggling to find a layout in which I can position one layout above another. The only way I could think of at the moment is to show the image as the background image of RelativeLayout not as AsyncImage but I believe there is a clean way to achieve this.

Class

<FriendTile>
    orientation: 'vertical'
    size_hint: None, None
    height: pic.height + username.height
    width: pic.width
    background_color: app.alert_color
    active_color: app.main_bcolor
    unactive_color: app.main_bcolor

    canvas.before:
        Color:
            rgba: (0, 0, 1, 1)  if self.background_color is None else self.background_color
        Rectangle:
            pos: self.pos
            size: self.size

    RelativeLayout:
        id: pic
        size_hint: None, None
        size: 100, 100

        CheckBox:
            size_hint: .1, .1
            pos_hint: {'top': 1, 'right': 1}
            canvas.after:
                Color:
                    rgba: (0, 1, 0, 1)
                Rectangle:
                    pos: self.pos
                    size: self.size

        AsyncImage:
            id: image
            size_hint: .9, .9
            pos_hint: {'center_x': .5, 'center_y': .5}
            source: root.avatar
            canvas.before:
                Color:
                    rgba: (0, 1, 1, 1) # if root.background_color is None else root.background_color
                Rectangle:
                    pos: self.pos
                    size: self.size

Expectations

Reality