You'll probably want to live with it and care for what's there until they get bigger. New plantings take several years to become well-established. Search the many threads here on pruning Paniculatas. Most can be treated similarly or the same.

I'd prune the broken branches, and if you are likely to get more similar storms, prune off some of the flower heads - bring them in for cut flowers. Often nursery shrubs have lots of flowers to help sales, but it isn't necessarily the best thing for a new plant to try supporting all of them. You will probably get many fewer flowers next year as the plant grows more roots and stronger branches. Years after that once they are established, the branches will be stronger and you will have lots of flowers.