The membership of the New Covenant was and is restrictive as to the quality and quantity of its members or those specially anointed to be of that class of people forming a Spiritual Israel of 144,000. sJW.
Like many self appointed so called wt scholars, you are confusing the New Covenant with the Kingdom Covenant. just repeating old unfounded stuff.
all the 12 tribes of Israel were in the Law covenant, only the kings & priests in their separate covenants. similarly
all of the 12 tribes (of Rev 7, the Israel of God ) are in the new covenant, The 144 000 of 7, 14, are in the special, kingdom and priestly covenant.
All of Israel of old partook, all the 12 tribes should partake. not just those that were sealed out of them. John 6.