Effective communication is key to conflict resolution. It includes learning to assert yourself without sounding confrontational. It is also key to practice active listening.
My focus in using clinical models include Restoration Therapy which is based on identifying the dysfunctional patterns of negative feelings and coping resulting in your pain cycle. Helping you then find your truths and strengths that lift your self-esteem, you would then learn how to move into your peace cycle. The rest is to practice, practice, practice!
Working with multigenerational families, sometimes it is helpful to point out to certain patterns of codependency or enmeshments. Learning then about healthy boundaries would be truly liberating!