Creating a surprise campaign for our loyal DM, but how can we content share?

Hi guys i was hoping that someone would be able to answer this for me. So having played anumber of games now me and a group of friends have always had our same DM and we are looking to surprise him by picking a campaign to play and have one of us DM for a change to give him a much needed experience playing as a character. Having been our DM for all our roll 20 experiences we have gifted him all content he/we needed to play our campaigns. If as an example i was to become the DM and buy a campaign to surprise him would i be able to access the gifted content he has when he joins? I have had a little read up on this subject about the creator needing to have the content but the creator can also appoint a GM/DM to allow them to have control over content but i do not know how that works exactly. Any help clearing this up would be greatly appreciated thankyou :) 

Yes and no, but no. I think you might not want to do it that way. If you Create the game on your account, Buy the game on your account, Install the game (module) onto a game that's created on your account..... then YES you can invite your DM to join that game, and you can "Promote To GM" so that he can run the game for you.  Since you're automatically a GM too since you're the owner, there is button for you "Re-Join as Player" so that you don't see the DM secret stuff while you're playing, while your DM is DM'ing it. That's cool. It works for many cases. The down side, your DM doesn't have 100% full control when they are just Promoted to GM of your tabletop. They cannot install the content onto their own tabletop. They do not own the files. The module is not in their account. They will depend on you, the owner, to install and configure parts of it. One of the things the Promoted GM cannot change is the Next Game Time. They can do most things, but they don't truly own the tabletop and so they are slightly limited in a few small ways. Work Around: Set up your own tabletop. Make a splash page that says "SURPRISE! We are buying you the _____ Rime Of Ice Module!!". A really fun thing, you can have all the Fellow Players sign the card, digitally, with the Roll20 drawing tool. On the page. After you reveal the surprise, just Gift the module to your DM's account, the way you've done it before, so that they have full control of installing it and making copies, and configuring every configuration setting the way they want it. If your goal is to save your DM time, you can ask THEM to promote YOU to a co-GM on their tabletop, and the DM can give you some Map Pages on which to perform set-up work with tokens, map tiles, handout creation, permission configs, and so on.

I think he wants to use all the content on his DMs account on his own account. Then he can make a fully content surprise campaign for him. I think you can go with a Deception Role on this one. Ask your DM to make a blank campaign and promote you to GM, so you can play with the content on your free time. Then gift him the module and start running it for him.

Yeah, i wanted access to the content we already gifted to him. Thankyou for the deception surprise suggestion if that is the best and only way to access all content then that is what i will go with :). Thankyou both for your responses!

Heads up, Sean.. You still won't be able to access all the art-packs on his account. As Co-GM you'll be able to manipulate (resize, position) any art assets (maps or tokens) that the Owner of those assets drops onto the Map Page. For example in that situation you might have to say "Hey DM I'm going to need all the Zombies to set up this adventure, can you put all the Zombie tokens onto the Sean's Map Page?"

Re: the "Deception Role" solution: Not sure if your DM is Pro and if you guys use api scripts. [I think] a co-GM does not have the ability to install scripts, so they might have to install those for you on the new game in which you were promoted.  Nope, my memory failed me. Co-GMs are good to go, as Gold points out below :)

Ahh, ok thankyou guys i'll keep it mind. Maybe i will just have to discuss it with him and come to some sort of solution. He is pro so hope that helps at least. Cheers guys you have been great :). The content i mainly wanted off of him was xanathars and other content thats more about the spells, races and subclasses. I make my own maps and tokens so i do not think they will be a problem :).

@ David, surprisingly I've found that the Co-GM can install and modify API scripts. I'm not sure if that is intended or safe, but they can do it. I've allowed The Aaron, Arcane Scriptomancer, into one of my campaigns to adjust the API scripts and he was able to, as a promoted Co-GM in my created game. @Sean yeah you would be able to access the Compendium in your DM's game. As a Co-GM you should be able to see everything that's in his compendium, the Xanathar's, spells, subclasses. You'd certainly be able to read the info there, same as a Player in that game could do. NOT sure if you can drag-and-drop monsters from there to tabletop as Co-GM. Test that. 

Ah, good to know, Gold! Thought I had tried that before, but glad that I was wrong!

Thankyou all very much guys, seems we have our usual sunday session on again (he had to fix his PC as it died) so i will notify him in one way or another on the day :)