The Hail Mary is not praying WITH Mary, it’s praying TO her.
You will never get the teacher of the other religion to admit it is praying TO their mary.
Of course it is. "Hail Mary." If it is simply joining her in prayer, then who is she "hailing" and praising as full of grace? In addition to the usual superlatives directed to her. Hailing and and praising herself? Praying "to" someone means directing prayers to them, addressing them, versus "let us pray." Christ is the only heavenly (and unceasing) intercessor btwn man and God (1 Tim. 2:5; Heb. 7:25) and we on earth do join Him with our own (inferior) intercessions, yet in so doing we also pray to Him, in praise and exaltation as we see in Scripture, which is nowhere given to created beings.
And when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints. And they sung a new song, saying, Thou art worthy to take the book, and to open the seals thereof: for thou wast slain, and hast redeemed us to God by thy blood out of every kindred, and tongue, and people, and nation; And hast made us unto our God kings and priests: and we shall reign on the earth. And I beheld, and I heard the voice of many angels round about the throne and the beasts and the elders: and the number of them was ten thousand times ten thousand, and thousands of thousands; Saying with a loud voice, Worthy is the Lamb that was slain to receive power, and riches, and wisdom, and strength, and honour, and glory, and blessing. And every creature which is in heaven, and on the earth, and under the earth, and such as are in the sea, and all that are in them, heard I saying, Blessing, and honour, and glory, and power, be unto him that sitteth upon the throne, and unto the Lamb for ever and ever. And the four beasts said, Amen. And the four and twenty elders fell down and worshipped him that liveth for ever and ever. (Revelation 5:8-14)
Catholic Mariolatry effectively puts Mary in there as an object to worship.