I believe I found them. I used the national online database of Belgium http://arch.arch.be
(you can choose english as language) and the passenger records on http://www.ellisisland.org
(information is in english)
Desiderius Engels °28/12/1876 in Bierbeek, married on 07/06/1900 in Bierbeek to
Maria Amelia Azijn °02/12/1880 in Bierbeek.
They were born and got married in Bierbeek, but later on they moved to Heverlee. They crossed the ocean by ship resp in 1909 and in 1910.
Interesting: Desiderius Engels was 5ft 5inch tall, had brown hair and blue eyes and had 40$ in his pocket when coming to the USA.