That is a great way to make greens and veggies for a large number of guests. And everyone will find something in it. I have used all different kind of veggies: beans, fennel, zucchini, cauli flower, potatoes, bell peppers or carrots. I have boiled the carrots, beans and tomatoes for about 7 minutes. The other veggies don't need more than 2-4 minutes. After I put the greens into the pan I have add a little sugra. That gave a wonderful caramel note to them and sweeten the veggies just a little. The greens were a hit. A great way to make them.
Dh really liked these greens and I followed the recipe using mixed baby greens from a local farmer's market. Although these tasted perfectly fine, I discovered I missed the stronger flavor of greens not cooked so long. Surprised myself.