Hi again,
The mystery remains re the Catholic marriage - cos you are right, the pre-requisites to getting married in the Catholic church were to convert, to bring the children up as Catholic, and the fact that Donald and Johanna had been together and had quite a few children before they finally got "hitched" wouldn't have gone well with the Catholic approach. I can't even see the "rules" being relaxed just because he was going off to War! Don't think the Church would have been so accommodating, unless either party could prove some "Catholicism"! Re James Stewart connection to Donald? Well, the Stewart NE families were numerous, - I only have 2 siblings listed for Donald - Mary born about 1875 in Stornaway, and Rachel Stewart b. abt 1888 in Rayne Aberdeenshire... (1891 census) - and 1901/1911 census give no further actual siblings... Would bet there were though. Very extensive confusing Stewart families some connected, some not.