I think the family went to England sometime after Martha died- remember that George would have been left with young children so perhaps his family helped look after them.
Found a marriage for a Gladys C. Scattergood Jan./Mar.1951 Brighton district to David Pask. (see freebmd.org.uk)
Possible matching death- Cladys Caroline Pask born 3 Jan.1909 died Aug.1999 Brighton district
Haven't found a death for Ida so I've removed day and month of her birth from your post in case she's still alive.
FreeBMD also lists a death which might be Kathleen-
Kathleen F. Scattergood, age 9, Jan./Mar.1925 Manchester South district
And a George F. Scattergood only a year or two younger than George Frederick Scattergood-
George F. Scattergood, age 42, Apr./June 1926 Birmingham South district
see replies 15 & 16