I am looking for my ex brother-in-law

I am looking for my ex brother-in-law. My two nieces want to find their father. My sister -in-law left him when they were 7 and 2. They are now 19 and 25. Their names are Jamie and Melissa. His name is James or Jimmy Patrick. He was raised in Middlesex, NJ. They lived in Toms River just before she left him. He stayed around there for awhile but we think he might have moved to Texas. He had a sister that lived there. I have his social security number. I sent a letter to SS and they responded back telling me that they had no know address for him. They did not mentioned if he was deceased or not. I tested their records with my mother and aunt who are both deceased and they both came up on their files as being deceased. I am hoping that he is not. I have called every James and Jimmy Ptrickl in the state of Texas that was listed. Everyone there was very nice but no one knew him. Is there anything else that I might try? I also called all Patricks in New Jersey that were listed but there was no relations. I have no idea where to turn. They are really anxiuos to find him the older one is married and three children that she would like him to see. My sister-in-law does not know anything about this and she will never know. That might be the one reason why he might not come forward because of her. He probably never wants to see her again. But he won;t have to. She lives in FLorida and so does my older neice. The younger lives here in New Jersey with my husband and I. So if anyone can help it would be greatly appreciated.

Check his Social in the death registry, that will tell you if he is deceased. With his name being common a middle name and DOB helps. Post it and the people online here can help.