Kathleen Cecilia Fea was born in Rosario, Argentina on 6th July 1877 to John Brooke Fea and Florence Maud Gunn.

She married George Gordon Sandys Lumsdaine on 25th November 1899 at Rosario, San Bart. George was born about 1867 in Edrom, Berwickshire, Scotland. He was the son of Francis Gordon Sandys Lumisdaine. His occupation was given was estanciero. Both Kathleen and George are stated to have been living in El Trebol at the time.

The witnesses to the marriage included Florence Elsie Chapman and Alfred Palmer Chapman. It is noted that Kathleen's sister, Florence Elsie Fea, married Frank Palmer Chapman.

Kathleen and George had a daughter, Kathleen Cristabel Lumisdaine who was born on 24th July 1900 and baptised St Bartholomew's Church, Rosario on 26th August 1900.