An occupation as Ground-Officer and a Tenancy passed on to a son-in-law?!

[SANTUDM]

Hello, I am from Buenos Aires, Argentina.
Not long ago, I found an advertisement of 1801, in which an Alexander Murdoch is mentioned as "ground-officer" on the Estate of Kildrummy (Aberdeenshire). Between my ancestors, I find an Alexander Murdoch who married Elizabeth Callum at Alford in 1771. An Alexander Murdoch is also recorded in the parish of Kildrummy as father of seven children (four sons and three daughters), and at those baptismal records, Alexander is recorded as living in "Moors of Wester Clova", "Moors of Clova", "Muirs" or "Moors". The allusions to "Moors of Clova", "Muirs" or "Moors" probably refer to the same farm: "Muirs of Clova", which is a different farm or croft to that one named "Wester Clova" (both on the Estate of Kildrummy).
Interestingly, I found another advertisement of 1782 with a John Callum in "Muirs of Clova". It does sounds as if he may be Elizabeth Callum’s father or brother (Alexander Murdoch's father-in-law), since I found a baptism records [29/10/1751] of an Elizabeth Callum, daughter of John Callum in Bridgend, Alex. and John Hay¿s? witnesses. I also found a marriage record for a John Callum in the parish of Towie with Elspet Hay. Posibly the same family.
The advertisement of 1782 that mentioned a "John Callum in Muirs of Clova" points the following: "FARMS to lett. That there are to be let, and entered to at Whitsunday next, for such a term of years as can be agreed upon, the undermentioned farms, belonging to Charles Gordon, Esq of Wardhouse, viz. (...) John Callum in Muir of Clova will shew the farms in Kildrummy, and James Strachan in Laighmuir those in Wardhouse. Offers for the above tacks will be received by the proprietor at Aberdeen, or by John Callun, or William Wood, overseer at Gordouhall".
Although John Callum is not mentioned as a "ground-officer", I think it is possible that he was (or possibly a Factor).
Do you agree with my conclusion? Or do you think it is a coincidence? Is it possible that John Callum in Muir of Clova had been a ground-officer (or factor) on the Estate of Kildrummy and that this position/occupation and tenancy over Muirs of Clova passed on to his son-in-law Alexander Murdoch in Muris of Clova?

[GR2]

Alex. and John Hay¿s?

In Scottish records it is quite common for the surname to be made plural if more than one person listed together has it. "Alexander Hay and John Hay" would therefore appear as "Alexander and John Hays".

It is not unusual for the job of ground officer to be passed down through the generations. One of my grandfathers was followed by his son and grandson as ground officer of the Delgaty estate in the parish of Turriff, Aberdeenshire, from the early 18th century until the early 19th century.

It is also quite common for a particular croft to be allocated to the ground officer. In some places it is referred to as the officer's croft.

[SANTUDM]

Dear GR2, thank you so much for your clarification comments. Your message it's very helpfull.