Twin, have never heard of it before your post, don't get me wrong i am not saying anything bad nor do i mean any disrespect to your family but sounds a little hinky to me, almost like a trial marriage the link references Scotland.
" "It was an ancient custom in the Isles that a man take a maid as his wife and keep her for the space of a year without marrying her; and if she pleased him all the while, he married her at the end of the year and legitimatised her children; but if he did not love her, he returned her to her parents."
" In the present day, some Neopagans practice this ritual. The marriage vows taken may be for "a year and a day," a lifetime, "for all of eternity" or "for as long as love shall last." Whether the ceremony is legal, or a private spiritual commitment, is up to the couple."
Taken from
Handfasting - Wikipedia, the free encyclopedia