Just a thought. In Game of Thrones, a groom will place a cloak with his house colors on the bride during the wedding ceremony, symbolizing that she is now a part of his house and under his house's protection.
What if: Clark and Lois (or, rather Superman and UltraWoman) exchanged some kind of cloak or sigil during the ceremony? Clark would put something with the El crest on it on Lois and she would place something with the UW crest on it on him. That way, both are accepting the other into their family but in an equal manner. (UW doesn't get swallowed up as El family "property", as I'm sure Lois would see it.)
