the igi has the following 2 entries, but no siblings that i can find - sorry.
JOHN MACKENZIE
Spouse: JEMIMA JUNOR
Marriage: 29 AUG 1838 Rosemarkie, Ross And Cromarty, Scotland
ALEXANDER MAC KENZIE
Male
Birth: 22 MAR 1841
Christening: 29 APR 1841 Rosemarkie, Ross And Cromarty, Scotland
Father: JOHN MAC KENZIE
Mother: JEMIMA JUNOR
hope this helps.
kind regards,
Lorna.