Not sure why you think Edward Haig was "in a disabled veterans home under alias Edward Higgs."In 1900 census he's clearly listed as Edward Haig- click on 'image' to see actual page-https://www.familysearch.org/ark:/61903/1:1:MMF1-WVJ
In the 1901 census Edward Haig is listed as an inmate in the Southern Branch National Home for D V S (this would be Disabled Volunteer Soldiers)His Military History is found in the colledtion labelled US National Homes for Disabled Volunteer Soldiers. It is within this record one finds him as Edward Haig alias Higgs. His tombstone appears to actually be marked as Higgs.PB
Married 25 March 1870- https://www.familysearch.org/ark:/61903/1:1:6TGV-J1FFNot sure what happened to children when mother Wilhelmina died-Joshua (born 31 Mar.1870) https://www.familysearch.org/ark:/61903/1:1:XYYP-HRJJohn (born 1872) https://www.familysearch.org/ark:/61903/1:1:F794-FG7Edward (born 1874) https://www.familysearch.org/ark:/61903/1:1:FQF9-HLF