I know it's a long time since your 2002 enquiry but this may help.
Daniel and Margaret(Rorke)Falvey were my ggg/parents. They had 7 children all born around Macclesfield, England. The second oldest Timothy born 1831 was my gt g/father on whom I hold various papers, certs etc.
Their youngest child was Margaret born 1847. Her birth is registered as plain Margaret and 'Marie' has never figured in her life from the information I hold.
In 1866 Margaret married John Dean in Macclesfield, England. Her name is shown on wedding cert. as Margaret FALBY which given Gaelic dialect/pronunciation is understandable. They had 2 children b. Martha 1868 and George b. 1871.
In the UK 1871 census they are living with Margaret's parents Daniel & Margaret Falvey at Heaton Norris, Cheshire.
Sorry, but I believe you have the wrong family for Margaret Marie Falvey although you did say this was not a proven fact.