How could I write a diary entry of one of the not so central characters of the story, with reference to characters that connect them.
I think that Mollie would constitute as a side character who has interactions with major characters. It will be a challenge to compose a series of diary entries from Mollie's point of view because she is so shallow as she featured in the narrative. However, I think that one diary entry can be how she does not like the idea of sacrificing her ribbons and sugar cubes. Perhaps, her interactions with Snowball on this point could be included. Snowball is the pig who tells her that the sugar and ribbons that she so loves are tools of human exploitation. The explanation goes over Mollie's head, unable to fathom what Snowball is addressing.
Another interaction could be when Clover confronts Mollie about her allegiance to the farm and the movement, in general. Mollie's diary entry here could talk about how she did run away from the farm and how she could not live without human beings. A diary entry from Mollie's point of view could reveal some level of insight into a character that is shown to be very shallow in the context of the work.