No church has authority to create or alter a sacrament contrary to God's Word.
The last meal that Jesus shared with his disciples before his death was a Passover meal.
This was a meal that the Hebrew people ate before they left Egypt. They escaped the 10th and final plague by putting lamb's blood on the doorposts of their houses; they ate the lamb, with unleavened bread, and other things as well.
Jesus, the 2nd Moses, rescued us from slavery to sin and death. The Hebrews were saved by the blood of a lamb; we are saved by the blood of the Lamb of God who came to take away the sin of the world, John 1:29. Paul says that Christ is our Passover Lamb who has been sacrificed for us, 1 Corinthians 5:7.
Jesus did take bread and wine; these also were symbolic because he is the Bread of life and the True Vine.
Regarding the meal itself; both Matthew and Mark say that it was
while they were eating that Jesus took bread, Matthew 26:26, Mark 14:22. Luke says that it was
after supper that he took the cup, Luke 22:20. So to keep this meal
according to the Bible, we should be reclining around a table, eating lamb and the other elements of the Passover meal. We should take unleavened bread during the meal and drink wine after it. In fact, I once went to a Passover meal given by a Jewish Christian, who said that there were 5 cups of wine drunk at a Passover meal - the one after the meal was, I think, the 3rd, but in any case it was known as the cup of suffering. So never mind stressing about having a tiny sip of wine; Jesus and his disciples would have had at least 3 cupfuls.
I suggest almost no one keeps this meal as Jesus did - a meal, during, or after which, they took bread and wine. So to argue that some people observe it better than others, when almost no one does what is described in Scripture, seems pointless. In 1 Corinthians 11 they had a meal, in Acts 2 they broke bread together - no mention of wine, of words being said, nor of anyone "officiating."
The important thing, for me anyway, is to remember that Jesus rescued us from death and slavery to sin. Jesus, the spotless Lamb of God, bread of Life and the True Vine, died for us, reconciled us to God and has led us to freedom - eternal life and reconciliation with the Father.
I believe that this is what God wants, what is important, what reconciles us to him and gives us life - I can't believe that he is going to get that hung up on the composition of the bread and the wine.
Oreos and Coca Cola will never be the Lord's Supper.
Yet I do believe that if that were all that people had, and wanted to remember the Lord's supper and offer them, and themselves, to him; he would honour that.