No service or work to which subparagraph (A)(iv) applies shall be treated as an assist for purposes of this section if such service or work—
(i)#
is performed by an individual who is domiciled within the United States;
(ii)#
is performed by that individual while he is acting as an employee or agent of the buyer of the imported merchandise; and
(iii)#
is incidental to other engineering, development, artwork, design work, or plans or sketches that are undertaken within the United States.