About Donald Maciver
I recommend you try to obtain a copy of "Account of the Clan Iver" by Principal Colin Campbell. My research on the Macivers is focussed on the Macivers of Tolsta, Isle of Lewis, Ross-shire. Quoting from the account .... John Maciver was Sherriff at Ness, and head of the clan A Bhaillidh - Macivers of Tolsta, Ness, Stornoway and Coll. From various sources including the above account the descendency then goes Kenneth - Duncan - Alastair - Iain - Donald - Alexander. It is only with this Alexander that some detail finally emerges (to my knowlegde).
This Alexander had twelve sons but only the names of six are known - Alexander, Roderick, Donald, John Murdoch and William. The third of these sons (Donald Maciver) was a tacksman of Tolsta who had six children - Alexander, Kenneth, John, Evander, Rev Murdoch and Isabella.
It is this Isabella Maciver who married Kenneth Mackenzie of Stornoway and whose children included Sir Alexander Mackenzie born in Luskentyre House, Stornoway in 1763.