Betsy-Tacy and Tib (1999)
Betsy-Tacy and Tib is a 1999 friendship book written by Maud Hart Lovelace and Lois Lenski.
After Tib Muller moves into the town where Betsy Ray and Tacy Kelly live, the eight-year-olds never quarrel, even when learning to fly--from the limb of a tree.