Sell multiple variants as 1 product

[Elze]

Hi! Maybe there is someone who can help me with the following: 

We sell 1 product with multiple variants. Variant 1 is from supplier 1 and variant 2 is from supplier 2. The variants both have a different cost price and SKU. 

Is there an app where it is possible to sell this as one product and when variant 1 has sold out it automatically sells variant 2? Or can I do this in Shopify itself and overlook it?

I hope I explained it clearly, if not please let me know.