Genealogy Chat

Can any one help me, I have been researching my tree but have come up against a brick wall on one branch of it. My grandfather was known as Roland John Marlow b 1894 (I thought). He died in 1947 so I never knew him. I found him on the 1901 census living in Battersea, as I expected, with his grandparents (although there seeem to be a very big age gap betwen them!). I tried searching for his birth record but could not find it. I then remembered my nan saying years ago that his name should have been Pritchard, I found one Roland Pritchard registered in 1893 in Lambeth. I sent for a copy of this certificate and this gives his mother as Louisa Pritchard formerly Marlow and his father as Thomas Arthur Horsehair Pritchard. I found a Louisa (aged 56) and John Marlow (aged 34)(Rolands grandparents?)on the 1891 census with a daughter called Louisa Pritchard aged 18. Until I got the birth certificate I assumed that that Louisa P. was Louisa M's daughter from a former marriage and I thought I had found them on the 1881 census living in Southwark. I even have a birth certificate for louisa Pritchard b1873 to William Pritchard and Louisa pritchard formerly Tipper. Now I am not so sure. I have searched for a Louisa Marlow born around 1873 but I can't find her. Unfortunately I have no family to ask; does any one have any suggestions or clues to look for? This is driving me bonkers!!