4 ideas
A landslide buries the line below a cutting just before a train is due. Roberta and Phyllis tear up their red flannel petticoats to make six danger flags, and when the train keeps coming Roberta stands on the track waving until it halts and she faints. The children's quick improvisation averts a crash, and the railway company later honours them with engraved gold watches.
When the children gather birthday presents for Perks the porter, he is furious, reading them as charity that marks him as poor. He accepts them gladly once he learns each came with a message from a neighbour who wanted to honour him for his own kindness. The same objects either shame or dignify the receiver depending on whether they signal pity or esteem.
The mother hides the father's imprisonment for espionage to spare her children, but the children read her tears and evasions and sense a hidden catastrophe anyway. When Roberta finds the truth on newspaper wrapping, she has to carry it alone and keep it from her siblings, repeating her mother's silence. Shielding children from bad news does not remove the knowledge. It isolates whoever discovers it.
The children wave every day at an old gentleman passing on the 9:15 train, and the ritual grows into a real friendship. When Roberta needs help, she writes to him, and his influence secures help for a stranded Russian exile and, in the end, the evidence that clears her father. Low-cost repeated contact with strangers builds ties that can later carry requests too large for any formal channel.