Chapeau is correct.It is the main village on Allumette Island opposite Pembroke, Ontario, settled originally about 1841.The name comes from a hat-shaped rock in Ottawa River that surrounds the island. The families actually lived at Demers Centre - a small crossroads on the fourth concession a few km south-west of the village, but St-Alphonsus de Liguori church where marriages, births, etc were recorded from 1846 on is in Chapeau.
Chapleau is a completely separate village in Nothern Ontario, a few hundred miles north of Sault Ste Marie. My grandfather, son of Georges & Angélique was the only Allard to ever live in Chapleau, where he owned a lumber mill from about 1900-1930.The town grew out of CP Railway construction in the 1880s.
Contrary to your repertoire, both Georges & Angélique, and Michel & Eugénie, were married in Chapeau.The two names are confusing and Chapleau seems to be better known, but is wrong in most instances of Allard history.