Appendix 2 the handbook quotes the Second Vatican Council,
"In the words of the apostle there is but one mediator: "for there is but one God and one mediator of God and men, the man Christ Jesus, who gave himself a redemption for all." (1 Tim 2:5-6) But Mary's function as mother of men in no way obscures or diminishes this unique mediation of Christ, but rather shows its power."Mary is a source of grace. We can pray to her with confidence.
Her power comes form her relationship with Jesus. We get a glimpse of their relationship in the miracle at Cana.
Mary knew there was a problem. She brought it to Jesus' attention when she said,
"They have no more wine."   John 2:3He was not inclined to do anything. Jesus said,
"How does this concern of yours involve me?"  John 2:4Mary told the servants,
"Do what ever he tells you."Jesus then turned water into a generous amount of excellent wine.
Mary interceded with Jesus. Even though He was not inclined to act, He performed the miracle at her request.
We can be confident that Mary will intercede for us also. And that Jesus will act.
Holy Mary, Mother of God, pray for us.