Really depends upon your definition of “add”.
Jesus said that those who worship God must do so with with “spirit and truth” (John 4:23,24), that it was necessary to to take in accurate or deep knowledge to gain life. (John 17:3), Paul said that those who approach God must believe that He is and becomes the rewarder of those earnestly seeking Him.
The Pharisees had the Scriptures and read them diligently but lacking God's spirit they couldn't understand them.
They didn't become the “men of God”.
So where is the “adding” in the above?
I'm not sure what you're asking. There IS NO adding as the Word of God doesn't need anything added to it. It is complete. As far as the Pharisees, they indeed lacked the Holy Spirit and therefore could not possibly understand the Scriptures.
"But God hath revealed them unto us by his Spirit: for the spirit searcheth all things, yea, the deep things of God'. (1 Cor. 2:10).