Agrarian

$array[$key] = array_merge(
    array(
        "Nom1" => 0, "Abs" => 0, "Nom3" => 0,
        "MarkFirst" => 0, "MarkSecond" => 0, "MarkThird" => 0,
        "RingWcf" => 0, "RingWcf2" => 0, "RingMono" => 0
    ),
    $row,
    array(
        "ColorGroup" => is_array($row['ColorGroup']) ? join(",", $row['ColorGroup']) : $row['ColorGroup']
    )
);

$array[$key] = array_merge(
    [
        "Nom1" => 0,
        "Abs" => 0,
        "Nom3" => 0,
        "MarkFirst" => 0,
        "MarkSecond" => 0,
        "MarkThird" => 0,
        "RingWcf" => 0,
        "RingWcf2" => 0,
        "RingMono" => 0,
    ],
    $row,
    [
        "ColorGroup" => is_array($row['ColorGroup'] ?? null)
            ? implode(",", $row['ColorGroup'])
            : ($row['ColorGroup'] ?? "")
    ]
);