Congratulations on your new baby bunny! It can be stressful for rabbits to be introduced to a new bunny and to expect that they will get along. From your rabbits’ perspective, it’s like being paired off without time for the bunnies to get to know each other. Bunnies bond for life, so it is important for them to get to know one another gradually. Set them up in side-by-side pens, or across from one another, and see if they can get along that way first. Try short play dates to see if they can be together without aggression. Some bunnies never get along with other rabbits and must be kept separated. Some people suggest taking both rabbits on a car ride together, to bond them more quickly, but I think that option is very stressful for the buns. Try keeping them in separate pens to start and then gradually work towards bonding them. Also, try offering them some food (tasty greens for example,) to see if they will at least eat together in peace. Bonding bunnies may take some time. If the older bunny continues to act out, it may be that she perfers to be a single bun! You can still have supervised play times; try to block their access to areas where they might dig. If that is not possible, try offering more interesting things to play with, like an old phone book, a tunnel, or grass squares to chew. Some bunnies are diggers, but you might be successful at limiting destructive behavior by providing a variety of other play alternatives, and by keeping them well supervised.