The new decree says:
"If a son, daughter, or grandchild of a Jew or of a Samaritan turns from the darkness of the Jewish superstition to the light of the Christian religion, their parents must not disinherit them, pass over them in silence in their testaments, or leave them less than they would receive if called to an inheritance on intestacy.
If this happens, the will must be rescinded and the aforesaid persons shall inherit as if on intestacy — excepting grants of freedom if made within the statutory number. If it can be clearly proved that such children or grandchildren have committed a grave crime against their parents or grandparents, then parents must still leave them one-fourth of the due inheritance, so that they may appear to have gained this in honor of their new, chosen religion." [CTh 16.8.28]
Clearly the Roman emperors don't want Christians to suffer any disadvantages from being Christian, not even within one's own family. People who convert to other religions can still be disinherited, but not those who convert from Judaism to Christianity.