Ferrer and Zola Mercelin were twin brothers from Montreal, Québec. They were both labourers and students and members of the Young Communist League and the Communist Party of Canada, as well as various organizations in Montreal. They arrived in Spain in the winter or spring of 1937. Zola served with the Rosa Luxemburg artillery group, then was assigned to the SIM to do work behind the lines. Ferrer served with the John Brown artillery and as a base clerk, and served time in an International Brigades disciplinary prison. Both brothers survived and returned to Canada. 

See record for Ferrer Marcelin

See record for Zola Marcelin