@Acolytus
I didn't understand it that way.
What I think he meant was that the Prince and Princess actually are the one making the Magic Tool.
She wouldn't leave at all, they would come to her to make it happen... and I don't think she has any good reason to refuse.
Having those two move for a few years into her Kingdom would be incredibly beneficial in terms of technological advancement and in terms of diplomacy.
The only problem would be the true origins of the King Consort... They would probably be able to get in contact with him a fair bit, and even maybe get access to the inner Palace... that could create some problems.
BTW, I love you TOOR, I love this manga so much, thanks for picking it up and thanks for the update!