welcome mtrancher,
We have Gelbvieh/Angus mother cows. We've experienced many sets of twins - 8-12 out of 350 cows for years. They usually come first, we know when the AI ends and the bull breds start when we have twins in the middle of calving. We purchased a Jersey and a Holstein a long time ago, we've bred them to Jersey and Angus, I make sure they are exposed either AI or to a bull early so when they calve we bring them in, keep them in a pen and when a set of twins is born and the mom has decided which one to keep, we grab the other one and put it in the pen with the nurse cows. Works great, it's like a happy commune, cows let any calf nurse on them (including their own) my only chore is to drop a round bale in their feeder when empty and I feed them extra cake every day. Bottle feeding calves is the absolute pits! If a cow loses her calf, I grab one out of the nurse cow pen and put it on her. Currently I have 3 nurse cows feeding 6 calves and they are growing well.