Was Rolf Scamander ever supposed to appear in the books?

Question

J.K. Rowling has said in interviews that Luna married a character named "Rolf Scamander". No character of this name ever appears in the novels. Did Rowling just invent him for the interview?

What happened to luna, did she get married who to?
J.K. Rowling: Luna became a very famous wizarding naturalist who discovered and classified many new species of animals (though, alas, she never did find a Crumple-Horned Snorkack and had, finally, to accept that her father might have made that one up). She ended up marrying (rather later than Harry & co) a fellow naturalist and grandson of the great Newt Scamander (Rolf)!
_{Bloomsbury Live Chat - July 2007}

And what happens to Luna?
J.K. Rowling: Oh, Luna marries um... Rolf Scamander, who is the grandson of a great naturalist, so they'd have a very interesting life, globetrotting and looking for weird animals. But I think she'd have twin boys. But later. That would be much later than this lot who all settled down earlier.
And are they happy?
Um, yes, I think so. My lot are all happy.
The twin boys have got names too?
Lorcan and Lysander. If that's alright with you.
_{JK Rowling A Year in the Life - December 2007}

Answer 1

Rolf Scamander was originally supposed to be a character in book seven

Evanna Lynch, the actress who plays Luna Lovegood, says that in her correspondence with J.K. Rowling during the writing of Book Seven, she learned that Rolf was a character who Rowling had tried fitting into the book.

Rolf Scamander was originally going to tell the story of The Tale of the Three Brothers in Harry Potter and the Deathly Hallows (which Hermione Granger and Xenophilius Lovegood did in the final version). J.K Rowling kept Evanna updated on whether he was in or out of the book.

Rowling and Evanna kept in contact when they were filming (Order of the Phoenix), and because Luna marries Rolf, she was keeping Evanna updated on whether he was in or out of the book, and it'd be, "he's in, he's out, he's in, sorry, he's out.
_{September 2015 Evanna Lynch interview}

Jo had told me that uh Rolf Scamander was originally in the book and I think he was supposed to have delivered the information that Xenophilius ended up giving in the book so I was just fascinated because she had been saying "oh he's out now, he's in again, he's out, he's in" and um it turned out that he was out, he never made it into the book.
_{December 2021 Evanna Lynch interview}