I found Alexander's death registration on Scotland's People. The informant was his son-in-law David Duncan and the place of death is given as Mosside, Parish of Ellon. This led me to Margaret's marriage to David Duncan and their children in IGI. This needs to be confirmed by reference to the original records.
Parent:
His father was John Mutch [J6]
Relationships:
Had a relationship with Isabella Norrie.
Children were: