Hi David just checked census records for them on Ancestry -
1881 Census - Living in Banchory as follows -
John Johnston aged 48 - born Fintray, Aberdeenshire - Unemployed Joiner
Margaret Johnston aged 34 born Keith.
Children - Elizabeth aged 10, William aged 9, Andrew aged 7, Isabella aged 5, John aged 2.
1891 Census - Margaret is listed as widow.
Sorry, still unable to understand what the problem is with SP
Hope this info helps,
Dorrie