Hospitality
The girls offer their hospitality to the nurse who cared for their dying father. This ends ironically, because the nurse is a homebody and a nuisance, and they do not get the privacy or intimacy they deserve to deal with their father's death. In a way, perhaps the nurse actually helps them by occupying the empty space around them. They are insulated emotionally, and by having a shared person to get angry about, the sisters bond. This is also the emotional space that their father no longer fills.
Mr. Farolles
After doing the right thing and regretting it, by letting the nurse stay over with them for a week, the town sends over a minister to administer any religious rites they might be interested in. The sisters decline his invitation to consume the sacrament, and he leaves. This is another highly ironic commentary on the girls. Although their father was a believer in authority, they are obviously not believers in authority. The girls decline the comfort of Communion because they are genuinely not interested whatsoever by religion.
The dramatic irony of domination
One's family dynamic can take all sorts of shapes as various people affect the culture of the home in their own way. The way the Late Colonel affected the home was by turning their family dynamic into a monarchy where he was the sovereign, and he staked that claim on his honor, on his leadership experience in the armed forces, and on his feelings of superiority. The reader knows this from inference, because the girls betray their home dynamic as they attempt to solve problems together. They seem unsure about anything, unable to commit. The reader can easily suspect the reason for this is that their ideas were not treated equitably by their father, and they are not used to having the final say, which they now have in abundance.
The curse of freedom
Although dominating anyone emotionally is damaging and often abusive, their is a secret pain that the father spared his wife and daughters by taking charge. Now that he is not there, the girls struggle to make any final plans or decisions. They feel flighty and unsure, not because they are inherently bad at decision-making, but because they have been deprived of responsibility by an overbearing parent. Now they come into true freedom, but it does not feel exciting or free; it feels daunting and amorphous, and they are disoriented emotionally by being truly free to cooperate however they each see fit.
The ironic organ
The girls go out to stop a neighborhood musician from merrymaking in front of their property. Suddenly, an ironic realization sweeps over the sisters: they don't have to 'Keep it down' anymore. They can be as loud as they want. They can enjoy music in the street. The organ is a call to adventure in some senses, because it takes them past the threshold of their known, fully-explored home dynamic, and it invites them to remember that life could have been a lot of different ways. Now that their family has changed, they get to pick what to do and who to become. They appreciate the irony of their father's influence, because there is no telling how much joy his demeanor stole from their lives.
