I’m pretty sure the Vigil Readings are an exception, as they do not constitute the normal mass readings but an introductory part, is this correct?
More generally, the liturgical books do allow a wide range of choosing which bible reading is read.
As I quoted, the 2004 Instruction Redemptionis Sacramentum has: “[62.] It is also illicit to omit or to substitute the prescribed biblical readings on one’s own initiative,”.
But this should be understood as within the wide range of choice allows. Some extracts from the Introduction to the Lectionary which highlight the choices:
“**a. Options in the choice of some texts **
78. The Order of Readings sometimes leaves it to the celebrant to choose between alternative texts or to choose one from the several listed together for the same reading. The option seldom exists on Sundays, solemnities, or the greater feasts in order not to obscure the proper character of the particular liturgical season or needlessly interrupt the semi continuous reading of some biblical book. On the other hand, the option is given readily in celebrations of the saints, in ritual Masses, Masses for various needs and occasions, votive Masses, and Masses for the dead. These options, together with those indicated in the
General Instruction of the Roman Missal and the
Ordo cantus Missae, have a pastoral aim. In planning the liturgy of the word, then, the priest should consider ‘the general spiritual good of the assembly rather than his personal outlook. He should be mindful that the choice of texts is to be made in consultation with the ministers and others who have a function in the celebration and should listen to the faithful in regard to the parts that more directly belong to them.’”
“
4 Weekday readings
82. The arrangement of weekday readings provides texts for every day of the week throughout the year. In most cases, therefore, these readings are to be used on their assigned days, unless a solemnity, feast, or memorial with proper readings occurs.107 The one using the Order of Readings for weekdays must check to see whether one reading or another from the same biblical book will have to be omitted because of some celebration occurring during the week. With the plan of readings for the entire week in mind, the priest in that case arranges to omit the less significant selections or suitably combines them with other readings, if they contribute to an integral view of a particular theme.
*5 Celebrations of the saints *
83. When they exist, proper readings are given for celebrations of the saints, that is, biblical passages about the saint or the event in the saint’s life that the Mass is celebrating. Even in the case of a memorial these readings must take the place of the weekday readings for the same day. This Order of Readings makes explicit note of every case of proper readings on a memorial.”
The Introduction to the Lectionary is available as a PDF document at
catholic-ew.org.uk/liturgy/Resources/Rites/RiteMissal.html .