So, I just noticed something about Lucina's alts. Take a look:
I think we all know these already, but those alts are based on characters from FE:A; from left to right, default, Nowi, Cherche. Cordelia, Tiki, Lissa, Tharja and Sumia.
With Tiki exception unless she marries male Robin, all of those are mothers tied to a future children, but none of those are able to marry Chrom. None, except for Sumia, who cutscenes and other material seem to imply there's a thing between she and Chrom. Not only that, the game itself pushes Sumia above all other possible Chrom wives when he has equal or none supports with all of them; and in Chapter 11 she's the only possible wive with a scene before Chrom's proposal.
So, what's the meaning of this? A confirmation of canon pairing? Deconfirmation? Or simply a homage with no other purpose?