I am sorry for not clarifying the topic of 'Ethiopia's Roman Brother...' This is an exerpt from Wallis Budge's translation of the Kebra Negast:
'And we will begin to tell you what we have heard, and what we have found written, and what we have seen concerning the King of RÔMÊ. The kingdom of RÔMÊ was the portion and dominion of JAPHET, the son of NOAH. And sitting down they made twelve great cities, and DARIUS built the greatest cities of their kingdoms: ’ANṬÔKYÂ (ANTIOCH), DÎRESYÂ (TYRE ?), and BÂRTONYÂ (PARTHIA ?), and RÂMYÂ (ROMA ?), and those who reigned dwelt there; and King CONSTANTINE built CONSTANTINOPLE after his own name. Now the sign of the Cross having appeared to him during the battle in the form of stars cut in the heavens, he was delivered out of the hands of his enemy; and from that time p. 122 onwards the Kings of RÔMÊ made their habitation there. And that DARIUS had many descendants; and from DARIUS to the days of SOLOMON were eighteen generations. And of his seed was born a man whose name was ZANBARÊS, and he made in wisdom a drawing of the astrolabe, and placed stars therein, and [he made also] a balance (i.e., clock) for the sun. And be [fore]saw what would come after, and that the kingdom would not remain to the children of JAPHET, but would depart to the seed of DAVID, of the tribe of SHEM. And when he thus saw, he sent a message to DAVID the King, saying, "Take my daughter for thy son"; and DAVID the King took her and gave her to SOLOMON his son, and SOLOMON begat a son by her and called his name "’ADRÂMÎ". And ZANBARÊS died before [this] and BALṬASÔR, who was of his kinsmen, became king. And he lacked male offspring to reign after him upon his throne, and he was jealous lest the children of his father should reign after him. And he sent a written message to SOLOMON the King, saying, "Hail to the greatness of thy kingdom, and to thine honourable wisdom! And now, give me thy son, whom I will make king over the city of RÔMÊ. For I have not been able to beget male children, but only three daughters. And I will give him whichever of my daughters he pleaseth, and I will give him my throne, and he shall be king, he and his seed after him in the city of RÔMÊ for ever."
And when King SOLOMON had read this letter, he meditated, saying, "If I keep back my son he will send to the King of the East, who will give him his son, and that which I have planned will be made void; therefore I will give him my son." And he took counsel with his counsellors of the house of ISRAEL, and he said unto them, "We have already given our son and our children to the country of ETHIOPIA, and ISRAEL hath a kingdom there. And now, so that we may have a third kingdom, p. 123 the country of RÔMÊ, I will send thither ’ADRÂMÎS my youngest son. Hold ye not it against me as an evil thing that formerly I took away your sons, for it is a pleasing thing to God that the men of ETHIOPIA have learned His Name, and have become His people. In like manner, the men of RÔMÊ, if we give them our children, will become the people of God, and unto us moreover shall be given the name of 'People of God', being spoken of thus and called thus: The people of ISRAEL have taken the kingdom of ETHIOPIA and the kingdom of RÔMÊ. Give ye your youngest sons as before [ye gave the eldest], and let those of middle age stay in our city."
And they rose up, and took counsel, and returned, and said unto him, "We will speak this matter unto the King, and he shall do his will." And he said unto them, "Make me hear what ye would say." And they said unto him, "Thou hast already taken the eldest of our houses, and now take the youngest of their children." And he was pleased with this counsel, and he did for them as they wished. And he set forward ’ADRÂMÎ his son, who took some of the nobles of the lower grades of the house of ISRAEL, and the lot fell upon him in the name of his father SOLOMON; and they gave him a priest of the tribe of the LEVITES whose name was ’AKÎMÎḤÊL, and they set ’ADRÂMÎ upon the king's mule, and cried out to him, "Hail! [Long] live the royal father!" And all the people said, "It is right and proper." And they anointed him with the oil of kingship, and commanded him to keep all the laws of the kingdom, and they made him to swear that he would worship no other god except the God of ISRAEL. And they blessed him as they had blessed DAVID his brother, and admonished ’ADRÂMÎ even as they had admonished DAVID, and they accompanied him on his way as far as the sea coast.
And SOLOMON the King wrote and sent a letter, saying, "Peace be to BALṬASÔR, the King of RÔMÊ! p. 124 Take my son ’ADRÂMÎ, and give him thy daughter, and make him king in the city of RÔMÊ. Thou didst wish for a king of the seed of DAVID my father, and I have done thy will. And I have sent unto thee his nobles, fourteen on his right hand and fourteen on his left, who shall keep the Law with him and be subject unto thee according to thy will."
And they arrived there with the ambassadors of the King of RÔMÊ, together with much splendour and all the equipment that was requisite for the country of RÔMÊ. And they came to the city of RÔMÊ, to BALṬÂSÂR the King, and they repeated all that SOLOMON had sent them to say, and delivered over to him his son. And BALṬÂSÂR rejoiced exceedingly, and gave him his eldest daughter, whose name was ’ADLÔNYÂ; and he made a great marriage feast according to the greatness of his kingdom, and established him over all his city of RÔMÊ. And he blessed him, for he was noble in stature, and his wisdom was marvellous, and he was exceedingly mighty in his strength.
And one day BALṬÂSÂR wished to test his knowledge in the trying of cases, a man, the possessor of a vineyard, having come to him and appealed to him, saying, "My lord, ’ARSÂNÎ, the son of YÔDÂD, hath transgressed thy word, and hath laid waste my vineyard with his sheep. And behold, I have seized his sheep and they are in my house; what decision wilt thou come to in respect of me?" And the owner of the sheep came to the King and made an appeal to him, saying, "Give me back my sheep, for he hath carried them off because they went into his vineyard." And the King said unto them, "Go ye and argue your case before your King ’ADRÂMÎ, and whatsoever he shall say unto you that do." And they went and argued their case before him. And ’ADRÂMÎ asked him, saying, "How much of the vineyard have the sheep eaten? The leaves, or the tendrils, or the young grapes, or the shoots by the roots?" p. 125 And the owner of the vineyard answered and said unto him, "They have eaten the tendrils and the branches that had grapes upon them, and there is nothing left of the vines except the twigs by the root." And ’ADRÂMÎ asked the owner of the sheep, saying, "Is this true?" And the owner of the sheep answered and said unto him, "My lord, they ate [only] the tendrils with leaves on them." And ’ADRÂMÎ answered and said, "This man saith that they ate the grapes: is this true?" And the owner of the sheep answered and said, "No, my lord, but they ate the blossoms before they had formed into grapes."
I hope that this provides some clarification.
About Ethiopians and other Denominations:
Currently, Ethiopia is about 60% Orthodox and 40% iSLAMIC, but this doesn't mean anything, because 'many are called, but chosen are few..." I believe that the Lord Christ uttered these words for a few reasons, but generally, it warns us not to be lukewarm--thinking that we are saved by Baptism alone.
Currently, there is a type of reform in the Ethiopian Orthodox Tewahido Church. It is inspired by the Holy Spirit through Pope Shenouda III and other great Church fathers (this is my opinion). The young people are very active in our Church, contrary to popular belief...
Pray for all the Christian people (militant and triumphant).
Sincerely in Christ our Lord,