"No One Should Have To Compromise Her Beliefs" and the Case for Incest

Reading the "morning briefing" of the NotReally Catholic Rundown, followed a link to a story wherein a woman whose office it is, as lay reader, (not "lector, LA Times, no matter what most Catholic say,) to read the petitions as requested by members of the congregation.
And one of them, she just could not, in good conscience, so the priest found a work-around, helped her to rephrase it in a way that didn't violate her sensibilities.
'Cause you know, freedom of conscience.

The petition, you see, was praying for, um.... religious freedom. You know, at a time when another woman had gone to jail rather than violate her conscience.
And the woman reading the Oddly Specific General Intercession just couldn't say words that might be seen to support the other woman.

Obviously obligations incurred in a civil service job are not the same as obligations incurred in service to the Almighty Triune God, and I'm not really faulting either woman here.

Because that's not really why, having followed the link, I bothered to read the article, that was because I had misunderstood a caption on the photo that headed it.

"[Mrs. X] kisses [Little Boy Y] in East Los Angeles. [Y] is the son of one of her two lesbian daughters. [X] will be travelling to Philadelphia for Pope Francis’ World Meeting of Families."

I thought it said "the son of her two lesbian daughters."

And I had thought, why not?
If, as Stephan Kampowski writes in Catholic World Report, society is trying to define "marriage" down to an association with no other reason for being than "the will of the partners," why shouldn't two sisters marry, and adopt, (or outsource, or engineer,) a child?

And what's it to any government, federal or state, to officially recognize marriages?

" The question is why any given union should be socially recognized as such. Are their reasons for it apart from the will of the partners? If the bond is socially recognized, then society would need to have a say in it. What interest would society have in recognizing a union, in giving it a certain status, and in endowing it with certain privileges? Married couples, who publically assume the state of matrimony also assume the munus, or office, of serving life in and through their relationship. Therefore their union evidently has social relevance: it is through marriage that a society is renewed; its new members are born and raised here, which is also the reason for the public interest of keeping this union stable."

Why not incest?

As it happens, I don't get along well enough with any of my sisters to live together happily as wife and wife, so it's a good thing Himself came along to rescue me from aged spinsterhood.

But I digress.
If the Church comes to recognize the "value" of homosexual unions, thus becoming more or less neutral on them, (you could say, "decriminalizing" as opposed to "legalizing," a distinction I've never quite gotten in the recreational marijuana rumpus,) why not of incestuous unions?
Such arrangements could also offer the stability of the public bond, deep affection,responsibility for children, (either from a previous "bond" or, as above, adopt, outsource or engineer,) and the ability to overcome trials, that is, mutual assistance to the point of sacrifice.
Arguments often take the form of reductio ad absurdum, but I think real life is rapidly descending into reductio ad dementiam.