How could we have a parent /child item relationship?

We are a trading company, buy and sell. When buying items, the same product from supplier maybe from different supplier's plant No. , and the quality is different. So we sell with different price. But we can only order with the same supplier product code. Any suggestion on this scenario?

We also need to make it suitable for internal order scenario.

We are at 12.1.3.

There maybe one possible way to make a parent item code and each supplier as child item code.