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The court case can be found using the namesearch link provided by Ashtone, search for Corpus and in document category select 'All'. In the first page of results there is a record for Mary and Kakio, the case concerned their marriage and what legislation applied due to her parentage. Sivero provides evidence about 6 pages in and a little later on.

There's a separate file relating to their internee status so you may see more than one record. It might be helpful to follow up with a search for Kakio (using forename and surname) as his documents also mention her family and various placenames in case any of those details help.

S_L

Couldn't post these yesterday (guessing you've already seen them).

Thomas Hallowes background in footnote:
https://archive.org/details/willsregistersmo00barwrich/page/130/mode/2up?q=brabazon

A family tree for Catherine & Thomas, have you tried looking at the births of the children in case that rules out a birth for practical reasons?
https://archive.org/details/FamiliaeMinorumGentiumVolume2/page/n63/mode/2up?q=brabazon

S_L

Merchant, see this page and the previous one
https://archive.org/details/scotspeeragefoun01paul/page/310/mode/2up

The parishes are explained on this page, the marriage is on page 22
https://archive.org/details/registerofmarria35edin/page/n5/mode/2up

S_L

Regarding 'keep off the grass', a reference to a grass widow maybe?

https://blog.oup.com/2009/02/grasswidows/

S_L

Mentioned in the abstract of a thesis at the University of Malta on Maltese newspapers from 1839 to 1939:
https://www.digivault.eu/
Select time period as year e.g. 1861
type as newspaper
subject try the likes of malta, gazzetta, giornale
I came up with an Italian language political paper that listed shipping news on the second page, the pages are individually linked as images towards the bottom of the selected search result (not all issues have been digitised)

S_L

The thesis is described here: https://www.um.edu.mt/library/oar/handle/123456789/39394