Since the Chinese assimilated the Manchus but what if China and Spain were under personal union...
Shunzhi Emperor marries a Catholic Chinese Woman and converts to Catholicism and decides to make Catholicism to be an official religion in the Qin Dynasty aside from Buddhism and Taoism and his child,Xuanye the future Kangxi Emperor is sent to a catholic school in the new world because of a suggestion of a priest to have him sent to a school in the new world to make him to be more faithful, knowledgeable and godfearing.
Charles II/Carlos II is born as Charlotte/Carlota, she is sent to Mexico in order to supervize it and to see the events in Mexico...Xuanye falls in love with Carlota and marries her and have twins one boy and one girl, then Carlota dies of ChildBirth..
Xuanye becomes Kangxi Emperor of China and King John of Spain and the new house that replaces Hapsburg is the clan of Aising Gioro..he becomes known as 'Juan el Chino' in Spain.