Complex sentence: From early 1840 Teresa, increasingly accompanied by Maria, performed in other places in France, including six concerts in April in Nantes, where, at that time, the first biography of the two gifted sisters was printed.
Split into simpler sentences: From early 1840 Teresa, increasingly accompanied by Maria, performed in other places in France. There were six concerts in April in Nantes, where, at that time, the first biography of the two gifted sisters was printed.