Premium add-ons bundle

I have a question that i can’t seem to find an answer to anywhere. If i buy forza horizon 5 as the base game with no dlcs on steam and then i’d like to buy the premium add-ons bundle on ms-store would that work? I know that you need to connect the game from steam to your xbox account so in theory it should but i don’t want to risk ~50$. In the end I apologize if i made any mistakes i’m not a native speaker:)

You can’t, or you buy all things from MS store or by Steam.

As mntioned above, it’s not possible, no…if you buy the base game from Steam, then you also need to buy the DLC from Steam.