The Four Entanglement

[Fuumayami]

I have an idea involving four characters.
A mom (43) and her daughter (18)
An older man (65) and his son (35)
The initial thought is that the mom and older man are neighbors. He lost his wife 2 years ago and the mom sympathize with the old man. It gets to the point where the mom and older man agrees to have sex (which idk how that would come about.)
Eventually this spirals to where their kids find out (on different occasions, not at the same time) and also get involved and they have threesomes and foursomes.

Your thoughts? How would they (Mom and older man) get started? How do the kids find out? Why would they want to participate? (My idea for the daughter is that she thinks her mother is selling her body to the older man and she's willing to sacrifice her youthful body for her mom? Idk doesn't really hold water.)
Would love to hear your opinions and ideas.
Thank you

 

[WCSGarland]

More details might help. Like is the mom divorced, married, single raising a bastardized daughter? I get the sympathetic reaction to the widower, but her motivation and background is kind of lacking from the original synopsis. And yeah, I get that you are kind of searching for her motivation. That's where the current circumstances can help. Such as, if she's married, is the current husband neglectful or abusive? If she's divorced, maybe she is thinking that the older neighbor might be more sympathetic and treat her more respectfully than the ex. Lastly, after a deadbeat dad, a more responsible more mature gentleman might be a welcome respite from having to shoulder the burden of raising a coming-of-age daughter.