An online tree has the married surname of Ernest's sister as WECKESSER. married 1937. The tree has no info about her parents or brother. It does say she was probably born in Victoria, BC, Canada.
Her parents married in Victoria British Columbia, Canada in 1916:
http://search-collections.royalbcmuseum.bc.ca/Genealogy/basicSearchMARRIAGE: 8 Feb 1916, Vesty First Church, Victoria BC
Robert MOFFATT 27, Bachelor, Soldier, b Ireland, Protestant, resident of Victoria BC
Father: Thomas MOFFATT, Shoemaker and Mother: Catherine LIDDLE
Annie CALDWELL 27, Spinster, Domestic, b Ireland, Protestant, resident of Victoria BC
Father: Robert CALDWELL, Carpenter and Mother: Marey BAIRA
(Note: the database indexes Annie as CADWELL, but the actual marriage cert does say CALDWELL)http://www.rootschat.com/links/0z10/ CEF: Attested 30 Sep 1918
Robert MOFFATT , age 26 yrs & 10mths
Residence: 1052 Mason Street, Victoria BC
Born: Caskel (or Gaskel?), Ulster, Ireland, 15 Jul 1889
NOK: Wife, Annie MOFFATT, same residential address
Occ: Carriage Builder
Currently in the Active Militia as a "Young Citizens Volunteer"
Description: (follow the link to see the Attestation form)
1921 Census: 2723 Graham St, Ward 2, Victoria City, BC
Head: Robert MOFFATT 32, b Ireland, imm 1913
Wife: Annie MOFFATT 32, b Ireland, imm 1912
Dau: Eleanor MOFFATT 4, b Victoria BC,
Lodger: Esther NUNN 53, b England
Cheers
AMBLY