I also work with adult family members who would like to improve their sibling relationships.
It may be that you have become aware that your current relationship with a brother or a sister is not how you would like it to be. The reasons for this may well be long-standing and complex. However, it is often possible with support and an openness from both people, to explore the origins of possible hurt and resentment and to create the foundations for greater understanding and closeness in the future.