What is the main conflict in The River at Green Knowe by L. M. Boston?

"The River at Green Knowe" is a young adult novel written by L. M. Boston and first published in 1957. It details the summer holiday adventures of three young children, of which two are displaced, and the third is the great-niece of one of the women renting the house of Green Knowe.

As the summer in the country village of Penny Sokey rolls around, and the culinary aficionado Miss Sybilla Bun and archeologist Dr. Maud Biggin decide to rent the river island manor of Green Knowe. They decide to host two children from the Society for the Promotion of Summer Holidays for Displaced Children. Maud also sends for her great-niece, Ida, to come and visit to keep the children company.