Sutton farm is the place where the hag aunty Ethel can send Mayrina's brothers Demir and Johl, if you will make the right choices during the dialog with her in act 1. Basically this is how you can save Mayrina's brothers, although dealing with a hag almost never has the happy outcome.
So where is Sutton farm? It is supposed to be in the north of Baldur's gate, and here is what I found...

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