The idea is you should be able to drag pawns from one spot to another and they should stick on the spot where you drop them.

board test

from kivy.properties import (
    ObjectProperty,
    NumericProperty,
    ListProperty
)
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.scatter import Scatter


class Spot(Scatter):
    pawns_here = ListProperty([])

    def collide_point(self, x, y):
        return self.ids.img.collide_point(x, y)

    def on_pawns_here(self, *args):
        for pawn in self.pawns_here:
            pawn.pos = self.pos


class Pawn(Scatter):
    board = ObjectProperty()
    where_upon = ObjectProperty()
    offx = NumericProperty(16)
    offy = NumericProperty(16)

    def collide_point(self, x, y):
        return self.ids.img.collide_point(x, y)

    def on_touch_up(self, touch):
        if touch.grab_current is not self:
            return
        for spot in self.board.spotlayout.children:
            if self.collide_widget(spot):
                self.where_upon.pawns_here.remove(self)
                spot.pawns_here.append(self)
                self.where_upon = spot


class Board(FloatLayout):
    pawnlayout = ObjectProperty()
    spotlayout = ObjectProperty()

    def __init__(self, **kwargs):
        super(Board, self).__init__(**kwargs)
        self.add_widget(self.spotlayout)
        self.add_widget(self.pawnlayout)

    def on_touch_down(self, touch):
        return (
            self.pawnlayout.on_touch_down(touch) or
            self.spotlayout.on_touch_down(touch) or
            super(Board, self).on_touch_down(touch))

    def on_touch_move(self, touch):
        return (
            self.pawnlayout.on_touch_move(touch) or
            self.spotlayout.on_touch_move(touch) or
            super(Board, self).on_touch_move(touch))

    def on_touch_up(self, touch):
        return (
            self.pawnlayout.on_touch_up(touch) or
            self.spotlayout.on_touch_up(touch) or
            super(Board, self).on_touch_up(touch))


kv = """
<Spot>:
    AsyncImage:
        id: img
        source: 'http://rltiles.cvs.sourceforge.net/viewvc/rltiles/rltiles/dc-dngn64/cdoor1.bmp'
        pos: root.pos
<Pawn>:
    AsyncImage:
        id: img
        source: 'http://rltiles.cvs.sourceforge.net/viewvc/rltiles/rltiles/dc-mon64/crystal_golem.bmp'
        x: root.x + root.offx
        y: root.y + root.offy
"""


from kivy.lang import Builder
Builder.load_string(kv)
from kivy.app import App


class BoardApp(App):
    def build(self):
        board = Board(
            pawnlayout=FloatLayout(),
            spotlayout=FloatLayout(),
            size=(400, 400))
        spots = [
            Spot(pos=(100, 100)),
            Spot(pos=(200, 200)),
            Spot(pos=(300, 300))]
        for spot in spots:
            pawn = Pawn(board=board, where_upon=spot)
            spot.pawns_here.append(pawn)
            board.pawnlayout.add_widget(pawn)
            board.spotlayout.add_widget(spot)
        return board

BoardApp().run()