For most of us, we do not sit around trying to figure out how to establish more authority in our churches. Unity maybe, but not authority. Either our churches have it or they do not. And for some, the word "authority" is even seen as a negative, because it is taken to mean building a hierarchical church structure, which is a big negative in many Protestant churches. Whether the answer is hierarchical structures or not, the Dong church does need some spiritual authority to tie them together.
Sure, they may have Jesus as their high priest, and those passages from Hebrews are in their chronological story set which is now starting to be used in churches, but they do not have anyone else. They do not have elder, experienced, Christ-like examples who can help them walk the way of Jesus. Individual churches do not even have leaders who could identify weak areas that need growth or even shepherd the flock in general.
Most Dong churches (we cannot speak for all, because we do not even know all) are groups of believers with no mutually-accepted leadership. And besides those, probably half of the known Dong Christians are individual believers with no gathering at all. It is not impossible for them to grow in Christ, but certainly close to impossible.
Let us pray for the Lord to raise up people and structures in the Dong churches which can provide the basic needs for spiritual growth. That will require unity: unity in the decision of who should lead local churches and unity if those churches are to be bonded together in any way. Please pray for authority and unity in the Dong church.