If that is considered a starting point, then it would lead to Angelica's mother. The song differs from plot in that Angelica is not an orphan (so far). She would have to be consistently groomed to think this way and would also need to be consistently connected to "the mastermind" somehow. That leaves her mother as her "father" is shown to be a victim so far.
If she is a true orphan then her "father" might not be her father. He may be simply charmed to think that. My current assumption is that he is. If he is not, then his eventual end will be an undeservedly cruel one which doesn't seem to fit the vibe of this story. It is quite possible that he is her father and, as is mentioned by Reirei, his innate affection for his daughter is the reason why the charm has spiraled out of control. His adultery will be the author's justification for his ending.
The other possibility is that Angelica is the witch herself and has convinced her mother to take her to her father. And, this song is only related because it uses a similar stereotype to superficially justify what Angelica has done.