Welcome to History Hub,
If it is a recent death? Their names might be in your friends obituary.
History Hub could be more help if you share your friends name.
I would suggest that you find the obituary for the friend and hope that it listed their children and perhaps the towns they lived in. Then use on-line searches for the individuals.
His name was John Mark Costantini. He was born in Trenton, New Jersey in 1958 and had not had contact with his family in over 30 years. His father's name was Serafino Costantini. I am trying to find as many children as he may have had from a past marriage. Thanks.
Dear Mr. Gonzalez,
Thank you for posting your request on History Hub!
In addition to the suggestions from previous posters, you may wish to search Ancestry, FamilySearch, and local newspaper archives for mention of John Costantini and his children. There may be a fee for using these services. Instead, please contact your local library. Many library systems subscribe to these sites, making them free for patrons.
We hope this is helpful. Best of luck with your research!