Squaring the Love Triangle

So you have a Love Triangle between Alice, Bob and Charles. However the tension can't be sustained forever, so finally Alice and Bob confess their love and all is happy. Except for Charles, doesn't he deserve true love? Well okay, but where can we pull out a love interest on short notice? Alice and Bob's baby! It would be like marrying the best qualities of both.

This Trope is about a love triangle being resolved from the product of the primary couple.

Not to be confused with developing the Love Triangle into a Love Dodecahedron. Subtrope of Love Father, Love Son. See also Unequal Pairing, which is likely in these circumstances.

As this is a Love trope largely focused around endings beware of spoilers.

WARNING! There are unmarked Spoilers ahead. Beware.

Examples of Squaring the Love Triangle include:

Anime & Manga

The Yuri Genre manga The Structural Formula of First Love by Shuninta Amano is about a lesbian whose high school love dumped her for a guy, but her daughter from him fell in love with the protagonist, in turn. It wasn't entirely intentional, however.
His and Her Circumstances

Literature

In Twilight, Bella and Edward end up together, but leave poor Jacob alone. Not to worry, when their daughter Renesmee is born he "imprints" upon her, essentially becoming romantically bonded for life with an infant.
In Anne McCaffrey's Talents books The Rowan/Afra/Jeff triangle gets resolved in favour of Rowan/Jeff and Afra is subsequently paired with their daughter Damia.

Live Action TV

A very weird one occurs in Doctor Who. Amy has Rory and the Doctor as potential love interests, and chooses Rory. They have a daughter who grows up to marry the Doctor. Whom the Doctor meets first, and likes before they know who her parents are. Complicated even further by the fact that they are all time travellers are are not all necessarily travelling in the same direction or at the same speed.
Variation in the original V where Robin Maxwell loved Kyle Bates, but he ended up with her rapidly grown child Elizabeth instead (although there was never a triangle in the first generation).

Video Games

In The Sims, this is a very common player tactic. See two sims you think look cool? Marry one now, have your kids grow up and marry the other.