Lavinia Saunders /La Grue

I am looking for information about Lavinia Saunders (La Grue) who was born on 17th August 1868 at the Kingstown Lying in Hospital in Co Dublin. Her mother was recorded as Lavinia Saunders, formerly La Grue, and her father was recorded as Matthew Saunders resident in Manchester England at the time. Although I have found census (1901 & 1911) and death records (both 1915) for both parents of the child Lavinia there is no marriage record. I have found no baptism, death record, census record for the child Lavinia or adoption record as they were not kept then. There are also census records for other La Grue family members both in Dublin and in England. The life of Matthew Saunders is well documented but I would like to know what might have happened to this child who was my grandfather's half-sister. I have searched all the available records online but she seems to have vanished without a trace.

Elissa Livingstone