Unknown to Jeff, earlier the same morning, while he was still slipping, Jennifer had seen the Chronivac and, knowing she would have time before everyone else woke up, she studied the thing. Of course she discovered what it could do and what had already be done with it and, while she was glad for all the changes thanks to some of them, she still wanted to make her husband pay for changing her without her say so.
So Jennifer had used the Chronivac to make Jeff unable to notice it wasn't in their room anymore until he either wanted to use it again, and placed next to the computer she had in her personal office at home, before going to prepare breakfast. (The others wouldn't sleep all day, after all.)
What she hadn't expected was for Shannon to hide in the first room she found once she fled her mother's lewd suggestions. There she found her mother's computer with this strange other one connected to it: the Chronivac. Jennifer had launched the Chronivac's install process on her computer, preventing its protection from activating.
Shannon explored the parameters and, unbelieving, saw it seemed to indicate the ability to change reality to her will. Was it really possible? She decided to start by changing how weddings worked, she didn't want peoples to continue looking down on her parents.
She created two kind of weddings. The first was extremely similar to what it was before Jeff had altered reality so he could be married to Jennifer, not that Shannon knew it. The second kind was extremely rare and caused by some unknown superior force, although it was hypothesized to be god or one of his angels. Peoples united by that second kind of weddings give off some kind of aura that make it clear that they are married and how. Such union were always seen as rightful, whoever was married this way.
That second kind of wedding also had for effect to annulate any of the other kind that would otherwise been in the way of the new one. Not only that, but any children born from a marriage was now seen as being from the new couples, even if the memories of who they are biologically related wasn't lost.
All this so Jeff would be the only one to ever be seen as her father, and make sure he would see her as his daughter. (Because, of course, she made it so Jennifer and Jeff were married this way.) Also, her biological father wasn't dead anymore, he just didn't care about Jennifer and Shannon anymore, just like neither of the O'Brian girls cared about him, all thanks to Jennifer and Jeff being married. (Her bio-dad was a jerk, anyway.)
But that's not the only thing special about this "married by god himself" kind of wedding. The moment the two spouse become married they feel the need to go hide somewhere and have sex together. She made it so it happened 2 month prior for her mother and Jeff, and then again between herself and Jeff just last night. Of course, since both weddings were divine ones, both were valid, and both of Jeff's wives were now pregnant.
Naturally, Jeff was ashamed of making love and being married to his own daughter, but with times and the help of his two wives he would come to accept that it's by a superior entity's will, probably god, that it happened and, as such, was something perfectly normal and acceptable, as new as it was to have it marry someone to two separate persons, especially one that also counted as his daughter.