I asked another forum member that has an ancestry.com subscription to look for passenger records for Ferdinando Riccardo traveling with two daughters in 1947-1948 to Argentina. Unfortunately nothing was found. I'm giving you the links to a couple of places that might be able to help you obtain information about your grandfather.
This link is for the Argentinian embassy in Canada. If you call them or email them and explain that you are seeking information about your grandfather they should be able to tell you where and how to get that information. For example......death certificate of your grandfather with cause of death etc. How to obtain a copy of the ships manifest.
The following are sites you might want to check provided you speak spanish or have someone that can translate for you.
The following information is provided by the LDS and gives you a basic outline for obtaining information from Argentina.
Municipal Archives and Local Civil Offices
The provinces are divided into departments which are divided into municipalities. Each municipality has a civil registry office, one or two notaries, civil and criminal courts, and a municipal government to administer all other matters. Every municipality has jurisdiction over their own archives, separate from the province archives. These offices are comparable to county courthouses in the United States.
In Argentina, civil records created by the local government, including birth, death, and marriage records, are kept in local municipal offices. These records are available to the public.
You can get information and copies of the records kept at the local civil offices by writing.
Inventories, Registers, Catalogs
Most archives have catalogs, inventories, guides, or periodicals that describe their records and how to use them. The National Archive has numerous, both published and manuscript catalogues, plus a card index. If possible, study these guides before you visit or use the records of an archive so that you can use your time more effectively.
Some of these guides are available at the Family History Library, at your public or university library, or through interlibrary loan.
The Family History Library has copies of some of the published inventories, and other guides, catalogs, directories, and inventories of these and other libraries. These types of records are listed in the Family History Library Catalog under:
ARGENTINA - ARCHIVES AND LIBRARIES
ARGENTINA, PROVINCE - ARCHIVES AND LIBRARIES
You can search the LDS website www.lds.org
for any of the above information.
I think your best option is to contact your embassy and have them instruct you on how to obtain records.
I'm sorry I couldn't be of more help to you. If there are any forum members that are familiar with obtaining records/information from Argentina, please jump in.
Please let us know what you decide to do and update us on your progress.