The Apostle Thomas, the doubter, when Jesus told him to put his fingers in the nail holes and his hand in the wound on his side, replied, "My Lord and my God". So here is an occassion when the singular "God" is referenced to Jesus Himself.
That help you a little? I agree that there is nothing in the scriptures that would give authority to pray to anyone other than God. Yes, both Jesus and the holy spirit were sent to do the will of the Father. One can't get away from that!
“You may not “recall”, so let me help you”
Thomas wasn’t there to hear Jesus say:(Jhn 20:17, “Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and [to] my God, and your God.”