Alexander George Milne was described as 'the brother' in the probate summary for George McLean [National Probate Calendar 1858], but appears to have been the brother-in-law: Alexander George Milne sen. described George McLean as his son-in-law and as the husband of his daughter Margaret in his will proved in 1849.
Other Relationships of Alexander George Milne junior
Son → Father
Other Relationships of George McLean
Son-in-law → Father-in-law