I don't have much on anyone in the early 1800's. John Bruce married Nellie Anderson sometime in the early 1800's but I don't have dates. He was born in the Parish of Liff and Benvie and is buried in Liff Kirkyard. I only have records for one of his sons: James Bruce. He was born in Dundee or Lochee April 12, 1838. He married Jane Alice Brown in Dundee on July 13, 1860. Jane and most of her children went to the US in 1889.
They were:
James who died in Belcher, Louisiana, 1948
Agnes Isles-died in Cheyenne, Wyoming, 1953
William Roger died in Detroit, Michigan, 1945
George McLean died in Kansas City, KS,
Jean who died in Cheyenne, Wyoming, 1943
Annie Chambers died in Kansas City, Kansas 1912.
Her oldest son John remained in Dundee to run the family store.

My Grandfather George Dysart Bruce was the son of Alice and James' oldest son John Brown Bruce. He came to the United States shortly after WWI , 1922, with a soccer team. He settled in the Kansas City Mo area.

Your Isobella could be a daughter of John and Nellie Bruce but I haven't found any records for him.
Sorry, I am sure this wasn't much help.
Good luck on your search!