[just as you can tell me that I can't say for certain that the originals and those that followed up until the oldest now on hand did have the DN there, I can tell you that you can't say for certain that it was not there.]
johnamos, the NT authors were quoting from the Greek Septuagint version of the OT. We know this because when the NT quotes the OT the wording is identical to that of the Greek Septuagint. Add to this the fact that the typical Greek Septuagint did not translate YHWH into any Greek equivalent name, but instead used the Greek for "Lord" (kurious). This is why every single NT text quoting a DN text of the OT uses "LORD" in places where the Hebrew text of the OT uses YHWH. They were not quoting from the Hebrew text. They were quoting of the common Greek translation of the OT.
Secondly, it is inconceivable that the name was originally in the Greek text of the NT but was thoroughly removed from every single copy with not a single one surviving. To think that there was a meticulous process of finding and destroying every single copy of the NT with the name YHWH was undertaken and successful so that no trace survives, is laughably ridiculous - on par with the most ridiculous conspiracy theories!
The evidence points to the very reasonable conclusion that the divine name was never in the NT because the authors were taking their OT quotes from a Greek translation that did not use the divine name. Saying that it was in the NT and then later removed with perfection, is to make an extraordinary claim that flies in the face of facts and reason.