It is a puzzle for sure with the names etc. Could be either/or really

David's children's names in order from [first] marriage in 1859 - all with a big question mark at the end subject to any form of Scottin naming pattern:
William 1861 - David's father's name from his 1859 MC
Isabella 1863 - Alexandrina's mother's name from her 1859 MC
John 1865 ?
David 1867 - David's father's name from his 1865 MC
Hugh Mcleod 1869 - Jane's father's name from her 1865 MC
Jane 1871 - David's mother's name from the 1859 MC
Mary Ann 1873 - David and Jane's mothers' name from his 1865 MC
John 1874 ?
However...we do have first William and Isabella with father David in 1871, linking up clearly the two families.
Monica