The Book of Blessings is an official liturgical book, the Latin edition was published in 1984. It includes “Order for the Blessing of a Family”. For this blessing within Mass, it has in the rubrics:
“62. … When the blessing of the family is carried out within a Mass celebrated in the family’s home, the rite must be arranged in accord with the principles and provisions of the Instruction on Masses with small groups, Actio pastoralis …”.
This document, Actio pastoralis, is also referred to the 2002 General Instruction of the Roman Missal: “32. Special celebrations of Mass should observe the guidelines established for them: For Masses with special groups, cf. Sacred Congregation for Divine Worship, Instruction Actio pastoralis, on Masses with special groups, 15 May 1969: AAS 61 (1969), pp. 806-811;”.
Here are some extracts from Actio Pastoralis:
“2. It is right to include the following among those special groups for whose benefit the eucharist may be celebrated:
… e. gatherings in the home, around the sick or elderly who are house-bound and can never take part in the celebration of the eucharist; included are neighbors and others taking care of such people;
f. gathering in the home on the occasion of a wake or other special religious occasion.
3. In most cases the eucharistic celebration for special groups is to be held in a place of worship.
4. The faculty of allowing a eucharistic celebration for special groups to take place outside a place of worship is reserved to the local Ordinary or, for his own houses, to the Ordinary of religious. But, especially when it is a question of private homes or institutions, they are to grant this faculty only if the place is suitable and decent. …
Futhermore, care must be taken that the concern for a more spacious and finer place does not lead to deliberate favoritism toward certain families and so to the restoration under another guise of the privileges that the Constitution on the Liturgy repudiates.”
The 2004 Instruction Redemptions Sacramentum also refers to Actio Pastoralis:
"[114.] … While it is permissible that Mass should be celebrated for particular groups according to the norm of law,
[footnote 203: Cf. Pope John Paul II, Apostolic Letter *Dies Domini