Ok found it. Page 20 in Thunder Rebels.
There are seven kinds of marriage among the Orlanthi in the 3rd age.
I have seen this too, but I was wondering about the 7 one, does this work like an engamement?
1, Husband and Wife - Equal status and rights. Children belong to his clan where the couple also live.
2, Husband and underwife - He has more property or status and has more say. As above otherwise.
3, Wife and underhusband - as 2, except the other way around. Children still belong to his clan though.
4, Wife and Esrolian husband - She has more status and property, and thus more say. They live with her clan and children belong to her.
5, Year-wife or year-husband - Temporary marriage, renewable afer a year. Children belong with their mother.
6, Bed-wife or bed-husbnd - No property changes hands other than that witnessed by others. The person not named raises the children.
7, Love-wife or love-husband - No property changes hands. This is a vow of monogamy for it's own sake or romantic love. Any children belong to the father.