Since 1865 a Welte showroom had existed in New York, managed by Edwin's uncle Emil, who didn't want to deal with his nephew's Mignon player.  So in 1906 Edwin Welte went to New York to direct the marketing for the new Mignon products.

Edwin found that the copyright to the name Mignon  was held by another piano maker, Wm. Knabe & Co.  Thus the instrument's first name in the States was "The Welte Artistic Player Piano -- In Europe, the Mignon".  The advert below, featuring a testimonial by Venezuelan aritiste Teresa Carreño, suggests that Welte soon licensed or otherwise gained control of the name Mignon.
 

ca. 1906 Welte Artistic Player-Piano  The Welte Artistic Player Piano Co.  18 East 17th Street, New York

ca. 1907 The Welte Mignon Piano  The Welte Artistic Player Piano Co.  398 5th Avenue, New York

In the third advert, from 1911, is an early appearance of the hyphenated name Welte-Mignon, and also the first use in a Welte advert of another name and phrase, Autograph and The Welte-Mignon Autograph Piano. At this time Edwin shared space in the showroom of his uncle Emil's firm, M. Welte & Sons, whose products included orchestrions imported from Germany and the Welte Philharmonic organ made in New York.