結局は、以下の部分の解釈の違いなのでしょうが…。
「Application to Sponsor and undertaking」(IMM1344A)の3ページ目の
6.b)
If the above address is not in the country of nationality of the person you are sponsoring, has that person been lawfully admitted for a period of at least one year in the country where he or she is living?