Not having seen the group photograph showing the sister Bridget that you mention, I have no opinion on whether that rules this photograph out as being Mary Jane Kelly. However, let me say that this photograph is not inconsistent with the supposed well-known newspaper representation of Mary Jane Kelly in Miller's Court, shown below, albeit that the drawing is probably conjectural. We know that sisters or brothers don't always closely resemble each other, so, on that basis, it's not inconceivable that the woman in this photograph and the image of Bridget that you say is unlike her could be siblings, is it? The question is whether you are satisfied that the family information you have been given is consistent with it being the family of the woman who was murdered in Miller's Court.
Best regards
Chris George

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