I found the Attestaton papers for 2 sons of Bertha Quibell at
www.collectionscanada.gc.ca/databases/index-e.htmlunder Soldiers of the First World War
Charles Edward Quibell
Regimental #763862
122nd Battalion
address on enlistment, South River, Ontario
b. July 15, 1899 Caddillac, USA
Next of Kin - Bertha Quibell, mother, South River, Ontario
enlisted March 1, 1917 at Galt, Ontario
Lewis Quibell, Regimental #724235
residence - Gooderham, Ontario
b. 3 January 1899, Michigan, USA
NOK - Mrs. Bertha Pearson
Portaville, Ontario
enlisted April 8, 1916, Gooderham, Ontario, age 17
second Attestation Papers for the same person using different forename
Lawrance Danamber Quibell, Regimental #1087312
residence - Lindsay, Ontario
b. 3 January 1899, Park Lake, Michigan
NOK - Bertha Quibell, South River, Ontario, Mother
he had spent 11 months in the 109th Battalion, Kingston and had been discharged for Heart trouble, re-enlisted April 7, 1917 Lindsay, Ontario
Interesting that his NOK in 1916 used surname Pearson and in 1917 using Quibell
I think it is entirely possible that the Bertha M. Brondi who was the witness at the wedding of Charles Quibell could in fact be his mother Bertha M. Quibell.
Perhaps when the 1921 census is available, some more questions may be answered.
It was not unusual for men enlisting to lie about their age as if considered too young or old they would be rejected. Also, women would tend to lie about their age as they grew older as well. Most would use the month and day of birth but the years would very greatly.