obliqua said:
Dig a wide hole, that will give you the room for the root growth of the roses. Many rose growers advise adding compost to the native soil to add micronutrients to the soil when you plant the roses. Roses do need a lot of food and water to keep them healthy and blooming.
Both roses are vigorous growers and should grow fine together. If one rose seems diminished in growth and vigor. I would consider moving it. Pairing of plants like these may or may not be successful. I often use the trial and error method in my garden.