Charles Wm., May 29, 1907 Miniota - mother Alice Preston
Margaret Annabell, July 27, 1908, Miniota - mother Alice Preston
Pearl Frances, Aug. 20, 1912, Miniota - mother Alice Preston
Charles Palmer, May 29, 1907 Miniota - mother Contstance Bowman ( from census I think this is same Constance as listed as Coybourne above - odd though)
note - father'snames are not shown
there is a marriage for Alice Preston and William Samuel Palmer, Dec. 2, 1903 in Birtle, MAN
there is also a death of a William Bell in Miniota Dec. 13, 1887, age 63 - the age seems to fit for Janet's father and another sign that they were in Manitoba by 1887.
Since in the 1891 census there is quite a gap between the two youngest children, one being born about 1880 and the other 1887 I looked to see if there were any children born in ON between those two, but did not find any and did not find any earlier children in MAN either.
Hope I didn't give info you didn't want, but wanted to show you what I found.
There are several Walter Palmers in the Western land grants database so maybe one will be your fellow.