Original sentence: After the death of the two possible heirs Gaius and Lucius, the only viable heir left was his stepson Tiberius, who was named his successor once he adopted Augustus' nephew Germanicus
Edited sentence: After a disappointing loss of his two most potential heirs Gaius and Lucius, the only viable heir left was his stepson Tiberius, who was named his successor once he adopted Augustus' nephew Germanicus