Avoiding stretch marks with a multiple pregnancy

One Happy Momma, 14 weeks pregnant, who has recently learned that I am expecting triplets. I am over the moon excited and blessed to have these 3 little lives inside me but, with that said, i am terrified about the prospect of stretch marks and sagging belly skin. I recently turned 40, I am only 5’3 with a typical average weight of 115, and my midsection is quite tone with muscle definition. I managed to avoid sagging skin and stretch marks during my pregnancies with all 3 of my other children (unfortunately only 2 live births). I had a terrible car accident 22 years ago and have a thick scar from sternum all the way down past my belly button. This scar has been with me most of my life giving it significant sentimental meaning and attachment. I have no idea if it will withstand the ever growing belly beneath it and pray that it does. My real question here is:
1. What will help to minimize the damage to my midsection during my pregnancy 
2. Has there ever been anyone that’s body did not have permanent damage following a pregnancy with multiples.. sagging, stretched skin, stretch marks
3. Are there any  Suggested products, exercises, and dietary recommendations