Interestingly, Ellis Island has a few of these going back and forth in the 1920s.(You should have given which YEAR of the censuses you found them in, and the birthdates, but I tracked them down anyway)
Young Alberic DeLaet is listed four times in 1922/1923 - once with mother Ruby, once with sister Yvonne, once with sister Muriel (crossed out; they probably didn't take this ship), and another with Alberic crossed out but Muriel remaining.
First four born +/- 1880, should be on 1881 Canadian: I think this might be them:
Name Marital Status Gender Ethnic Origin Age Birthplace Occupation Religion Albelie DELAET M Male Belgian 39 Belgium Mercht. Catholic Cecile DELAET M Female American 24 Q Catholic Adoner DELAET Female Belgian 5 Q Catholic Evan DELAET Male Belgian 4 Q Catholic Martha DELAET Female Belgian <1 Born: Aug; 8/12 Q Catholic Josephine PILGRIM Female Indigenous 19 Wendras Servant Episcopal
Source Information: Census Place Ste-Antoine Ward, Montreal, Montreal, Quebec Family History Library Film 1375855 NA Film Number C-13219 District 90 Sub-district H Division 4 Page Number 69 Household Number 308