Cambi, in a passage quoted above, writing at the end of March 1520( ?), says that two were raised for Giuliano, Duke of Nemours, and Lorenzo, Duke of Urbino, and that the Cardinal meant one to be for himself.

The fourth he does not speak about.

It has been conjectured that Lorenzo the Magnificent and his brother Giuliano, fathers respectively of Leo and of Clement, were to occupy two of the sarcophagi; and also, with greater probability, that the two Popes, Leo and Clement, were associated with the Dukes.
Before 1524 the scheme expanded, and settled into a more definite shape.

The sarcophagi were to support statue-portraits of the Dukes and Popes, with Lorenzo the Magnificent and his brother Giuliano.

At their base, upon the ground, were to repose six rivers, two for each tomb, showing that each sepulchre would have held two figures.