I am doing Dawnguard before the main quest with this character. As such, I have been given the quest Discerning The Transmundane during the Dawnguard questline, a quest which is also part of the main questline.

I just wonder what I need to watch out for, glitch-wise, when doing the quests kind of out of order. Particularly when a third quest for the Oghma Infinium also intersects with the other two.

Is it advisable to complete Oghma Infinium before the main quest, or is it better to wait until after the main quest sends you for the dragon scroll (even though I will likely be carrying around the said scroll for life at that point)?

Any thoughts on doing these three quests would be appreciated!

In all my playthroughs of DG I have never done the MQ first, I always do the DG quest first. No problems. Instead, what you happens is that when you go to meet Parthunax, he goes through the normal dialogue and then when he tell you to get the scroll, you just tell him you already have it. The quest then procedes as if you had returned with the scroll from Blackreach.

The Discerning the Transmundane is not part of the main quest line. The main quest line leads to this Daedric quest, but the Daedric quest can be done seperately. But the Scroll is quest item that can't be removed from your inventory until you finish both the DG quest and The Fallen from the MQ.

Thank you kindly for your answer. That also means that I could, if I so choose, finish the Deadric quest before completing the main quest, because our friend the rambling scholar dies during the Daedric quest.

You don't have to even started the main quest to get the scroll. You can just waltz into Septimus' hideout and start the quest whenever you want. Order in which the quest is done does not matter.

On UESP, though, I thought I read somewhere that if you run straight there and do the quest before encountering the request in the main quest to fetch the scroll, that it could fail/glitch because the guy who you are supposed to talk to about the scroll is killed at the end of the Oghma Infinium quest. No one in this discussion seems to be concerned about that, though.

Thanks all for their thoughts. I just got to Blackreach for the first time with one of my characters.

All the main quest needs is the elder scroll. Plus Septimus doesn't die until the end of the second part of Discerning the Transmundane.

My character Aussie grabbed the scroll while she was down there doing the quest for Septimus, so long as you have the scroll I do not see why there would be a problem with the main quest. But I was not taking the chance on leaving the scroll there and it mysteriously vanishing when I needed it later. Aussie is probably never going to complete the main quest, she likes enjoying the quiet life with hardly any dragons in Skyrim, but best to be sure and keep the scroll. So I did not mind when we needed it for Dawnguard, at least it finally was useful for something.

Thanks for both the question and the responses - I started a new game for Dawnguard, and am doing Dawnguard before even getting started on the main quest (thanks to an Alternate Start mod) - the quest when looking for the dragon scroll has come up in my journal saying something about Paarthurnax, who my character does not even know exists (even though I do, in a metagaming sense!) and I was worried I might have broken something (and the journal entry is a little immersion-breaking given that my character has never heard of Paarthurnax, oh well!) So I'll be OK to do the Dawnguard quest now, carry round the Elder Scroll, and just be like "oh I already have that" at the appropriate point in the MQ? Good to know, thanks.

The real question I think is why do we even get the Dragon scroll? We never use it we only read the blood one and the dragon scroll doesn't factor into the questline at all. Unless it's part of the dawnguard side I have no idea what the point in it was.

The only real thing I've noticed that you need to watch out for for potential breaking is if you never fought the dragon Mirmulnir at the watchtower outside of whiterun, then I hear Durnehviir doesn't spawn in the soul cairn.

Not true, I fought Durnehviir in two DG playthroughs, one before starting the MQ, and the other after finishing it.

You read the dragon scroll in the glade to help locate the bow.

I think it's the Blood Scroll.

no you definitely read 3 different elder scrolls in the glade, you just initiate the reading of all 3 with the blood scroll

Part of the prophecy that Dexion sees is that all of the events in Dawnguard will occur when dragons return. That is where the seemingly pointless Dragon scroll comes from.