The GNRHS regrets we cannot answer your questions on locating relatives who worked for the Great Northern Railway. All GN personnel records were disposed of/destroyed at the time of the Burlington Northern merger in 1970. You may want to join the GN Online Discussion group and post your genealogy question there. For additional resources, try the following links:
The Railroad Retirement Board will search records for a fee (post-1936 only): archives.gov/atlanta/public/railroad-retirement-board-records
Ancestry.com provides an online-searchable database of RRB records, though membership is required to view the results: ancestry.com/search/collections/61597/
The Minnesota Historical Society has genealogy information at: www.mnhs.org/genealogy
John Phillips, III has created a very helpful genealogy reference entitled Genealogy and the Northern Pacific with info relevant to any railroad.
There is also a railroad-related genealogy site at: www.cyndislist.com/railroad.htm
Many GN and NP records are stored at the Minnesota Historical Society in St. Paul. Their website has a search engine.