This is not exactly what you are asking for but it’s similar. Paul prayed and encouraged others to pray for his dead friend Onesimus in 2 Timothy
16 May the Lord show mercy to the household of Onesiphorus, because he often refreshed me and was not ashamed of my chains. 17 On the contrary, when he was in Rome, he searched hard for me until he found me. 18 May the Lord grant that he will find mercy from the Lord on that day! You know very well in how many ways he helped me in Ephesus.
Also Revelation5:8 and 8:3 clearly show the saints praying for the church
Jewish tradition of which Christianity comes prays to those in heaven.
All Christians did it until the 1700’s
Hebrews 12 also makes it clear
Therefore, since we have so great a cloud of witnesses surrounding us, let us also lay aside every encumbrance and the sin which so easily entangles us, and let us run with endurance the race that is set before us,
But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to myriads of angels, to the general assembly and church of the firstborn who are enrolled in heaven, and to God, the Judge of all, and to the spirits of the righteous made perfect, and to Jesus, the mediator of a new covenant, and to the sprinkled blood, which speaks better than the blood of Abel. (Hebrews 12:1, 22-24 NASB)
We are surrounded by a great cloud of witnesses…the Saints.
We come to “the spirits of the righteous made perfect” … The saints.
So it seems the burden of proof is on you to say why your 300 year old novelty is true.