Hi, I'm Rugged Indoorsman's wife.
Thank you so much for your response. This is the scenario we're slowly working out, and we'd very much like any feedback of the following nature: 1) Is it plausible? 2) What should we be careful of to avoid any major faux pas?
In the story, the background of the main characters begins with two patrician families (or one patrician and one very rich equestrian). The main family is patrican, however, either way.
In the history of the main family (patrician), the man is married to a woman and has at least two sons and one daughter with her, perhaps more. However, he has fallen in love with the wife of another man (either another patrician or equestrian family). He gets her pregnant while her husband is off doing whatever (possibly war, or if equestrian, business). When the cuckold comes home and finds his wife pregnant, he's furious. Either he kicks her out (and does not divorce her) or he makes it clear he'll never acknowledge the child and she walks out on him. Having nowhere to go (perhaps her family is upset over her betrayal), she goes to her lover and tells him she is pregnant with his child. He sets her up in a villa and essentially takes her to be his mistress. She has the baby, a girl, and he adopts her.
At this time perhaps the husband of the mistress may get into some legal battle with the patrician over 'their' daughter. My understanding is that patricians were well neigh unassailable in court by lower classes, so I imagine that the patrician would handily win the case if his opponent were equestrian, and perhaps some bribery to officials may go in if the 2nd family is patrician. In any case, despite the mechanism, the daughter is adopted by the patrician pater familias.
Eventually, the wife of the pater familias dies and so does the husband of the mistress. They may or may not marry, but at this stage they're venerable anyway and the story is about their kids.
The main characters are the girl-child who was adopted and older legitimate-born sister. There's several issues between the two, from jealousy over looks to the fights over dowry for the adopted girl (as there's less money for the elder). The girls are in competition over everything, but eventually it boils down to a fight to get better husbands. Once married, the rivalries continue as each one tries to outdo the other in making their men more powerful. Ultimately, they both unwittingly (or not so unwittingly) set powerful men against one another to cause political havoc.
Thanks for your time!
-E