Well, it fits with the ego of the character.

No, it doesn't. Erica stakes claim like nobody's business when it comes to her children: "My daughter, Kendall. My daughter, Bianca." But miraculously, she doesn't claim her grandchildren?

I kinda like that they do that. It's sort of like a running joke amongst the show and hardcore viewers.

It's ridiculous. I don't find it amusing. If Krystal, who has a daughter younger than her grandchild can call Little Adam her grandson, then Erica, who has three grown ass children needs to start calling her children's children her grandchildren. It's far beyond "cute" or "funny." It's tired. All of this bullcrap about "it fits the character" and "character this" and "character that." Sing me a story, sing me a rhyme. Erica is territorial. If it's truly in character, she'd stake her claim on those children with pride. Her men belong to her. Her children belong to her. But she'll generously let Miranda, Spike, Ian and Gabrielle belong to her daughters? That crap does not "fit" the character.

I'm done.

But miraculously, she doesn't claim her grandchildren?

Erica's just vain as hell.