Can you play Minecraft Online with an Xbox SILVER account?

I have an Xbox one, and the main account on the Xbox (algaeeater), Has gold and has purchased minecraft.

But my girlfriend has a silver, and she also plays minecraft online with me. How can she join me in a joinable online minecraft room (splitscreen), if shes silver?

Is it because it's splitscreen, and I own the game on a gold membership?

And if she got on her account, and played MC by herself. Would it let her play online with a silver, even tho the game is purchased thought a gold?

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