[IDEM libro tertio decimo responsorum. ] §28.6.46.prPater familias primis tabulis postumo herede instituto secundis sibi uel filio, si intra pubertatem decessisset, Gaium Seium fratrem suum substituit, deinde Titium Gaio Seio, et postea sic dixit: 'quod si Gaius Seius frater meus primo loco substitutus heres mihi esset, tunc Titio fideicommissum relinquo'. quaero, cum filius patri heres exstiterit eoque intra pubertatem mortuo frater testatoris ex substitutione heres sit, an fideicommissum debeatur, cum ita relictum sit, si Gaius Seius frater suus sibi heres extitisset. respondi fratrem defuncti, qui in utrumque casum institutus uel substitutus est, filio impubere defuncto ea quae testator reliquit praestare debere: nec aduersari haec uerba 'quod si Gaius Seius mihi heres erit, tunc dari uolo', cum uerum sit eum et testatori heredem exstitisse.
[The same, from his thirteenth book of Opinions.] A paterfamilias, having instituted a posthumous child as heir in the first tablets of his will, substituted in the second tablets his brother Gaius Seius for himself, or for his son if he should die within the age of puberty, and then substituted Titius for Gaius Seius, and afterwards spoke as follows: "But if my brother Gaius Seius, substituted in the first place, should be my heir, then I leave a fideicommissum to Titius." I ask, when the son has become heir to his father and, upon his death within the age of puberty, the brother of the testator is heir by virtue of the substitution, whether the fideicommissum is due, since it was left on the condition "if his brother Gaius Seius should have become his heir." I replied that the brother of the deceased, who was instituted or substituted for both cases, is obliged, upon the death of the pupil son, to pay what the testator left; and that these words, "but if Gaius Seius shall be my heir, then I wish it to be given," do not stand in the way, since it is true that he has also become heir to the testator.