The Ivanka as first lady talk was probably spurred by this article. It portrays Melania as shy and reticent, and Ivanka as putting herself out there.
http://www.politico.com/magazine/story/2015/10/ivanka-trump-donald-trump-2016-213248?o=1
Personally, I don’t see this idea holding up. Shy first ladies are often very popular and the public knows who is the real first lady.
“It portrays Melania as shy and reticent”
Perfect. We don’t need a President’s wife who thinks she is empress.