They don't defer, they just stop defining it and define exactly what they already do, a legal contract between two consenting adults.
If they don't define it, someone else will. Who?
Just stop calling it a marriage and call it a civil union.
Why? What does the government or anyone else gain by doing this?
Again they don't defer they stop defining it and using the term civil union instead.
Again, why do it this way?
There is conflict and controversy in the term that used to be defined through religious systems. So the government should just drop it and use civil unions instead.
Why should they? The government should be resolving conflicts, not running away from them.
If another body wishes to issue a ordained union under their system they may do so and call it what they wish but alone it would have no legal authority itself and would only work inconjuction with a legal civil union. If the term they use is married then so be it but the government should top using the term.
Fine then.
I'm a body -- in fact (true story!) I'm an ordained minister who has performed 2 wedding ceremonies (and one vow renewal).
I have not yet had the honor of performing a same-sex wedding ceremony, but if asked, not only would I gladly accept, but I would waive my standard fee for my services (which, by the way, comes to exactly $1 plus expenses)
My weddings are every bit as valid and recognized as one performed in any church, courthouse, synagogue, mosque, drive-through Vegas chapel, Temple of Aphrodite... whatever.
Therefore, by the power vested in me as an institution unto myself, I hereby recognize any and all "civil unions" sanctioned by the government to be...
marriages, in every sense of the word.
Furthermore, let it be known that on this day, June 12, 2021, I grant full permission to absolutely ANYONE to invoke my authority as an institution to declare their own "civil union" to be a marriage.
And just like that, we're back where we started.
The sisters don't get married. They get a civil union. Their rights in this relationship allows each to have full custody to a child or matters of joint finances, tax breaks, health issues or death and any other rights afforded to a "married" couple without being married.
All of which they either already have by being related, or would indicate anyway by naming one another as the beneficiary on their relevant legal documents... just as they would with a spouse.
I'm not aware of all the legal overlap sisters can currently have with marriage but that was merely an example and you are free to replace 2 sisters with 2 consenting friends who do not have a sexual/romantic relationship but seek a legal union.
A legal union without sex or romance? That's marriage after a few years.