Hi David
I tried some additional research today but was unsuccessful.
The period it concerns means that data from birth registries and population registries / census are not yet online for Antwerp & Hoboken.
The data from these registers is available from the Antwerp archives, on premis as micro-fiches but I don't live near Antwerp.
Also the Familysearch Reseach centres would have these files available, but again in (some) of their centres and not yet online.
I searched for the name of Monville in older archives (up to 1900) in Antwerp and in Hoboken, but the name doesn't appear in those. So that suggests to me this family may have arrived in Antwerp in the early 1900s, but from where is than the big question.
As said, the archives from 1925-1930, to look for the birth Diane Monville, are not available online yet and that makes it that much harder to research your question.