Meaningful Face Resemblance

Is that a trope? When two people share face and body features not to be genetically related but to represent a plotline connection, like in Kingdom Hearts? Sora to Roxas to Ventus to Vanitas as well as Kairi to Naminé to Xion?

- Roxas resembles a strawberry blond Sora with shorter hair because he's a undead counterpart of Sora - Ventus resembles Roxas because Ventus' emotions went inside Sora - Vanitas also resembles a black hair Sora because he's made up of Ventus' bad emotions

- Naminé resembles a blond longer-haired Kairi because she's the byproduct of Sora giving both Ventus' and Kairi's emotions back to their original selves. Technically, Roxas and Namine are made up of an half of Sora's body each, with an half of Sora's soul each, but take after Kairi and Ventus respectively, because Kairi and Ventus' emotions were released alongside Sora's body and soul - Xion resembles a black hair shorter haired Kairi because she's cloned from Sora's memories and Kairi was Sora's strongest memory

I don't think this is tropeable, especially because all the examples you listed have an in-universe reason (if they aren't genetically related they still have a reason for resembling the main characters).

The fact that they have reasons make the resemblance have meaning, and thus there's a trope here.

Yes, but this seems ill-defined and generic. How does one determine if resemblance is "meaningful" or not? Must it signify an in—universe connection or can it be purely thematic? Maybe its just that the proposed name needs to be changed, as this seems to open up misunderstanding and Trope Decay.

The meaning is in the context given, usually.

There's also Identical Stranger to compare to.