I was able to sort out some of the problem. Michael was most likely the the son of John and Maryas stated on the 1870 census:
John Urban age 43, born France
Mary, age 40, born Pennsylvania
Cecelia, age 19, born Louisiana
Annie, age 17,born Louisiana
Michael, age 12, born Louisiana
John, age 3, born Louisiana
Justine, age 11 months, born Louisiana
No actual family relationships are stated on the 1870 census
Jumping forward to the 1880 census:
Obrist Urban (female) age 50, born Pennsylvania
Catherine, age 30 (no relationship shown) b. LA, father France, mother Penn.
Michael, age 23, son, b. LA, father France, mother Penn
John A. age 13, (no relationship given) born LA, father France, mother Penn
Justine M. wife [that's what it says], age 11, born LA, father France, mother Penn.
I don't know why only Michael is shown as son and the others with the obviously erroneous exception of Justine are not shown with any relationship to the head of the household.All the other families on the page show each member of the household with clearly designated relationships.
What to make of all this? To complicate matters further, Obrist is shown as both married and widowed. (Both blocks are checked)
Obrist could be Mary Obrist?
Catherine in 1880 could be Cecelia in 1870?
Annie, 17 in 1870 is out of the house in 1880
Michael, John and Justine are all accounted for, and at the correct ages, so we are pretty sure this is the same family iin both census records.
Now, just to complicate matters even further, I went back to the 1860 census in New Orleans. The only John Urban was:
John Urban, age 35, born Westphalia, Germany
Caroline Urban, age 34, born ""
Antonio Urban, age 8, born""
Josephine Urban, age 3, born Louisiana
Mary Urban, age 1, born Louisiana
No sign of what should have been 2 year old Michael, or a Cecelia or John. There were no other heads of houshold named John Urban anywhere in Louisiana, but Michael was reported on the 1870 and 1880 as being born there, so where were they in 1860?
Hopefully, some of this helps and doesn't serve just to confuse matters.
Bill St. George