From the 2002 General Instruction of the Roman Missal (GIRM) approved for the USA, which can be accessed from romanrite.com/girm.html :
“68. The Creed is to be sung or said by the priest together with the people on Sundays and Solemnities. It may be said also at particular celebrations of a more solemn character. …”.
The Book of Blessings, in describing a blessing within Mass, would need to have something specific to reverse this. I have not looked up all them, but to give an example from the Order for the Blessing of a Married Couple, on the Anniversay of Marriage it has “100 The general intercessions follow, either in the form usual at Mass or in the form given here.” This comes after the blessing ceremony, which is after the homily.
There is nothing specific enough here. The creed’s omission is not mentioned. It is not discussed whether this is a Sunday or Solemnity.
It also has for this blessing:
“93. While maintaining the structure and chief elements of the rite, the minister should adapt the celebration to the circumstances of the place and the married couple and the families involved.”
“102 In the liturgy of the eucharist the Order of Mass is observed, with the few modifications indicated.
As circumstances suggest, the husband and wife may bring the bread and wine to the altar for the presentation of the gifts.”
Both of these indicate the subordinate nature of the Book of Blessings to the instructions of the Roman Missal for the celebration of Mass.
Reference: Book of Blessings, Liturgical Press, Minnesota, 1989, ISBN 0-8146-1875-8, pages 20-24.