Dear Eutychus,
How truly lucky you are to have such a great Saint as a relative!!
Rome and also the local Church bishops/Primate can declare patron saints. Canada, as you know, has ten so far which include St Joseph, St Anne and the secondary patrons, the North American Jesuit Martyrs.
The Venerable Pope John Paul the Great, when canonizing a saint, would sometimes declare him or her a patron of something. He declared St Thomas More a patron of politicians/legislators and Sts Cyril and Methodius co-patrons of Europe with St Benedict.
The rule seems to apply that local patrons for a region can be declared by the region’s bishops via their Primates. But it is often the case that a profession, for example, will want to have a particular saint as its patron and one can apply for permission to the Church hierarchy to formally have such as one’s patron.
St Anne was made patron of Canada in 1636 by the Jesuits who received this permission directly from Rome. They also applied to Rome to have “Our Lady of Huronia” be the Marian patron of what is now Ontario and the indulgence which is attached to this devotion is still extant and applicable.
There is the story about how the early lawyers got their patron saint. A representative was sent into a church yard where there were statues of saints and he was to go around the church three times, blindfolded, and the first statue he was to lay hands on was to be the lawyers’ patron.
After he circumambulated three times (he was obviously led by the hand), he grabbed something and shouted, “We have our patron! We have our patron!”
When he removed his blindfold, he saw that he had grabbed hold of the devil on which St Michael the Archangel was standing . . .
Alex