Plotly how to subplot template image/logo

Hi plotly people,

I try to build a plotly layout template which places a logo in the center of the figure. The following code works great for non-subplot figures but it obviously does not work for sub_plots generated by make_subplots(). In subplots the template only places one big logo in the center of the area due to xref and yref = ‘paper’.
In order to get a separate logo in the center of each subplot I assume I would have to calculate the center position of each subplot?
Any ideas or solutions to this problem?

pio.templates["my_template"] = go.layout.Template(
    layout=dict(
        plot_bgcolor=plot_bgcolor,
        # margin=dict(l=50, r=50, t=50, b=20),
        colorway=my_colorpalette,
        hovermode='x',
        font_size=12,
        xaxis={"showline": True,
               "showgrid": False,
               "linecolor": grid_color,
               "mirror": False,
               "zeroline": True,
               "zerolinecolor": grid_color,
               "zerolinewidth": 1,
               "ticks": 'inside',
               "tickcolor": grid_color},
        yaxis={"showline": True,
               "showgrid": False,
               "linecolor": grid_color,
               "mirror": False,
               "zeroline": True,
               "zerolinecolor": grid_color,
               "zerolinewidth": 1,
               "ticks": 'inside',
               "tickcolor": grid_color},
        images=[dict(
            source=logo_image_source,
            name='logo',
            xref="paper", yref="paper",
            x=0.5, y=0.5,
            sizex=0.35, sizey=0.35,
            xanchor="center", yanchor="middle",
            layer="below", opacity=0.1
        )]


    ),
    data=dict(
        scatter=[
            go.Scatter(marker=dict(symbol="diamond")),
            go.Scatter(marker=dict(symbol="square")),
            go.Scatter(marker=dict(symbol="circle")),
            go.Scatter(marker=dict(symbol="triangle-up")),
            go.Scatter(marker=dict(symbol="triangle-down")),
            go.Scatter(marker=dict(symbol="star")),
            go.Scatter(marker=dict(symbol="x-thin"))
        ]
    )
)

Cheers Amadeus