The Diatessaron by Tatian is at least the best-known earliest attempt to harmonize the four gospels: Matthew, Mark, Luke and John. I think it was the evangelical scholar Mark Strauss who wrote that all attempts to harmonize the gospels are uninspired, unlike each of the four gospels which indeed are inspired by God.
That thought should help us begin to understand the importance of letting each passage and book of scripture be read as is, to stand on its own, to get the message it’s conveying before comparing it with any other passage or book. Bibles which have heavy cross references are helpful only if you keep this in mind and put it into practice, otherwise I think they’re unhelpful. The NRSVue at least in the electronic version now available (before hard copies are available hopefully by mid-August) have nice cross references added, but only to the extent that it helps one with the present passage, proper background for that at least so far in what I’ve seen.
Some like to say that the Bible is 66 books in perfect harmony, and that only God could have done that. What instead ought to be said is something like the Bible is 66 books (and I would like to add the apocrypha/ deuterocanonical books to at least be read seriously alongside it) that are disparate and often contradictory, but find their fulfillment, correction, and final meaning in God’s revelation in the good news in Jesus. Also some like to say that Genesis 1 and 2 are one creation account, and the NIV translates it so that it appears to be the case. But a more literal translation helps us see that we are likely looking at two creation accounts, each written to bring out something important, and not meant to be meshed together.
The point here is that we need to let each passage and book stand on its own, turn it over and over again in its own context. And do the same with the rest of the Bible. In the end I’m thinking that what we find is God helping many disparate strands somehow come together in Jesus and the fulfillment Jesus brings. Every single passage and book of the Bible is inspired on its own, telling us something important for us, for our understanding. In the end every part is to be seen in the light of Christ, his coming and all involved in that, his death and his resurrection, and all that follows.
So be careful with the idea that scripture interprets scripture. Only Christ interprets scripture, and we need to let each passage say precisely what it’s saying on its own and let the light of Christ shine on that. In and through Jesus.