@ Sea Breeze - The origins of 1 John 5:7 are widely known. The source material of the King James Version, the Textus Receptus,
adds a reference to "the Father, the Word and the Holy Ghost." This
phrase is not found in any of the earliest manuscripts, and wasn't even
in the earliest produced copies of the Textus Receptus.
As for Matthew 28:19, either the verse was 'doctored' or Luke, Peter, & Paul were seriously
deficient in their writing/ baptism teaching.
(Acts
2:38) Peter said to them: “Repent, and let each one of you be
baptized in the name of Jesus Christ for forgiveness of
your sins.
(Acts
8:16) For it [the holy spirit] had not yet come upon any one of
them, but they had only been baptized in the name of the Lord
Jesus.
(Acts
10:48) With that he commanded them to be baptized in the name of
Jesus Christ.
(Acts
19:5) On hearing this, they got baptized in the name of the Lord
Jesus.
(Acts
22:16) Rise, get baptized, and wash your sins away by your
calling on his [Jesus'] name.’
(Romans
6:3) Or do you not know that all of us who were baptized into
Christ Jesus.
(1
Corinthians 1:12, 13) "What I mean is this, that each one of you
says: “I belong to Paul,” “But I to A·polʹlos,” “But I to
Ceʹphas,” “But I to Christ.” Is
the Christ divided? Paul was not executed on the stake for you, was
he? Or were you baptized in the name of Paul?"
(Galatians
3:27) For all of you who were baptized into Christ
have put on Christ.
Eusebius
Pamphili, or Eusebius of Caesarea was born about 270 A.D. and
died about 340 A.D. and made eighteen
citations of Matthew 28:19, - always in the following form: "Go
ye and make disciples of all the nations in my name,
teaching them to
observe all things, whatsoever I commanded you." Only after the Council
of Nicea in 325 C.E. did he start to use the 'triune' wording.
WikiPedia: “There
are a number of nontrinitarian scholars who claim that the
development of baptism "in the name of the Father, and of the
Son, and of the Holy Ghost" is a post-Apostolic Age
interpolation and corruption and that the "Trinitarian"
clause in Matthew
28:19
- “...baptizing them in the name of the Father and of the Son and
of the holy spirit,” was added in the 2nd/3rd century. They cite as
evidence that no record exists in the New Testament of someone being
baptised with the Trinitarian formula, using literal interpretation.”
https://en.wikipedia.org/wiki/Baptism_in_the_name_of_Jesus
If you can provide any scripture which mentions all 3 - outwith the two discussed - I'd like to read them.