Debug Output:

Drawing ID 1 at (0, 0) -> SVG (0, 400) Solo children for ID 1: 20, 21 Drawing ID 20 at (0, 1) -> SVG (0, 470) Drawing ID 20 at (0, 1) -> SVG (0, 470) Solo children for ID 20: 24, 25 Drawing ID 24 at (0, 2) -> SVG (0, 540) Drawing ID 24 at (0, 2) -> SVG (0, 540) Solo children for ID 24: Drawing ID 25 at (1, 2) -> SVG (120, 540) Drawing ID 25 at (1, 2) -> SVG (120, 540) Solo children for ID 25: Drawing ID 21 at (3, 1) -> SVG (360, 470) Drawing ID 21 at (3, 1) -> SVG (360, 470) Solo children for ID 21: Drawing ID 18 at (4, 0) -> SVG (480, 400) Drawing ID 22 at (5, 1) -> SVG (600, 470) Drawing ID 22 at (5, 1) -> SVG (600, 470) Solo children for ID 22: Drawing ID 19 at (6, 0) -> SVG (720, 400) Drawing ID 23 at (7, 1) -> SVG (840, 470) Drawing ID 23 at (7, 1) -> SVG (840, 470) Solo children for ID 23:

Positions:

Array
(
    [1] => Array
        (
            [0] => 0
            [1] => 0
        )

    [20] => Array
        (
            [0] => 0
            [1] => 1
        )

    [24] => Array
        (
            [0] => 0
            [1] => 2
        )

    [25] => Array
        (
            [0] => 1
            [1] => 2
        )

    [21] => Array
        (
            [0] => 3
            [1] => 1
        )

    [18] => Array
        (
            [0] => 4
            [1] => 0
        )

    [22] => Array
        (
            [0] => 5
            [1] => 1
        )

    [19] => Array
        (
            [0] => 6
            [1] => 0
        )

    [23] => Array
        (
            [0] => 7
            [1] => 1
        )

)