I think the Bible doesn’t make it mandatory to have a ceremony to recognize a union, but it recognizes that the only way that one can honour marriage is to be committed to a person of the opposite gender permanently, without straying.
Anything less is a strike at the foundation of it.
Indeed I do not think the Bible makes a ceremony mandatory.
These are not new questions at all. The reason is that questions about rights of married persons and hereditary rights of their children probably pre-date any recorded history.
I’ve read entries about marriage in many of the legal dictionaries and NONE of them say a ceremony is required. In fact, a ceremony can be performed, but in most cases the marriage STILL does not exist until it is consummated.
Here are a few of the things that courts might look at:
Are they living together as man and wife?
Have they made an open declaration of their intent to marry?
Have they consummated the union?
Are there offspring involved?
Has she taken his name or he taken her name?
Have they, as a couple, acquired property in both their names?
Now once again none of the above taken by itself is considered conclusive. But these ideas and this same concept is recognized in every society that exists or has ever existed worldwide.
Anderson’s Dictionary of Law calls it the oldest and most important transaction in life, the basis of the fabric of all civilized society.
NONE of the law dictionary entries I have ever read define marriage as being anything else than a relation between a man and a woman, who openly chose to and consent to a perpetual union.