Interesting that in the 1920 US Census, the two adopted girls have different birthplaces for their parents; ie, Stella is born in Argentina, but her parents are noted as both born in Italy. Olinda is also born in Argentina, but her parents are noted as both born in Argentina. Would this not suggest that Olinda is not a natural daughter of Maria, but perhaps a step-daughter?
Italo's birth date is given as 11 December 1907 in Manhattan (Ancestry.com). There is also a death record for him on 7 August 1929 in the Bronx.