In all my playthroughs I managed to miss Auntie Ethel in the grove. So my introduction to her was a seemingly random encounter at the entry of the swamp. Standalone, I found that conversation a bit forced and strange, as she got into my face when I asked what she had been doing to that girl. I mean, before I take sides, I want to actually know what is going on. As a motivation to explore a rather significant portion of the map, I felt that this was particularly weak, which led to my original question.
If she was supposed to tell me in the grove that she was able to remove my guest, it would have been all the motivation I needed. I do know asked myself how I missed her. I thought I had explored the grove quite thoroughly. Just goes to show...