Question regarding cross save

It makes sense, but it doesn't help my case. I shouldn't have mentioned my PC Account as it confuses People.

So i have a Xbox Account with Warmind and Curse of Osiris. I also have created a Steam Account a couple hours ago so there's nothing on it for now.

The Question is if i have to buy those Expansions again on Steam and additional if i need to complete those dlc Missions again as it is an Expansion.

Because i cant imagine i will get Forsaken for my second Account since i bought it on a completely different Account.On the. other Hand, there's Steam Family Library, but im. not sure if that helps my Case.

So in Conclusion : Do i have to buy the dlcs again as it is a new Platform or do i get to keep it? Or am i missing something with New Light? Its just about the Expansion itself, im aware i will keep Shaders, Gear and everything else i unlocked.

(The Question about the Gamertag is irrelevant now as i assume i will have the Name i've choosen on the specific Platform.)

/r/destiny2 Thread Parent