Well, a change in sovereignty isn’t actually in the list that Malden Capell proposed. The point that I’m making, though, is that you can have an overal system of government with more than one legislative body, and the balance of authority between those legislative bodies can change incrementally, through normal constitutional/legislative mechanisms, without violence, revolution, coups, etc. When that happens, the system of government overall is continuous, even if there are marked changes within the government as to where power lies.
That’s exactly what has happened in England/UK since 1688. In 1688 the monarchs had real political power. Today they have almost none. And yet, it’s a continuous system of government, one that has gone through changes and developments in three centuries, but continuous.
In the case of Canada, that’s exactly what happened. The last change in government through violence, conquest, etc., happened in 1763. Then, you had a government system where the bulk of the power lay with the British Parliament, and some power lay with the colonial legislatures. Over time, the British Parliament devolved power to the colonies, and the colonies merged into a federation, which in turn gradually acquired greater and greater authority by devolution from Britain, to the point where the British Parliament eventually lost all power.
After two centuries of this development, you certainly have a completely different government, but the point is that if you’re looking for a continuous government, that’s what you’ve got.
Another way to look at it is legal continuity. I’ve cited laws in a legal brief that date from 14th century England which are in force today in Canada. I’ve cited English court cases from the 17th century, which are still of legal effect here. It is a continuous system of government, different from those in the US, which have a marked break in the political structure/sovereignty/legal continuity in the late 18th century.