The literature so far seems to indicate that involving family members in psychotherapeutic interventions for patients diagnosed with Severe Mental Disorders (SMD) such as psychosis or bipolar disorder is effective, reducing hospitalizations and increasing treatment satisfaction. However, interventions with such characteristics have not been found for patients with Borderline Personality Disorder (BPD), one of the disorders included under the umbrella of SMD. Therefore, it seems necessary to develop and implement comprehensive programs involving families, given the benefits observed in other SMD diagnoses such as psychosis or bipolar disorder.

BPD is one of the personality disorders that receives significant clinical attention and research, with suicide being one of the most associated problems with this diagnosis, ranging from 3-10%. The prevalence of BPD in the general population is considered to be around 1%, rising to 12% in clinical populations and 22% in hospitalized patients. Meta-analysis studies place Linehan\'s Dialectical Behavior Therapy (DBT) and Bateman and Fonagy\'s Mentalization-Based Therapy as the two interventions with the highest level of recommendation. Another widely supported intervention is Blum\'s Systems Training for Emotional Predictability and Problem Solving (STEPPS) program, especially effective when delivered in a group format within clinical and hospital settings due to its high adaptability. However, the issues described concerning patients with BPD inevitably lead to severe consequences in their work, emotional, and social environments. Relatives of individuals with BPD are more likely to experience psychological problems, burden, and depression. Generally, when family members participate in treatments, the patient\'s relapses decrease, recovery becomes easier, and overall family well-being improves. Presently, interventions for relatives of patients with BPD exist. Family Connections (FC) has received the most empirical support. Nevertheless, to date, there have been no studies analyzing whether adding intervention programs for family members contributes to an improvement in the STEPPS program, which is precisely the aim of this current research. Specifically, the objective of this work is to compare the effectiveness of the STEPPS protocol for patients with BPD and their relatives, compared to the STEPPS protocol for patients alone and the Family Connections program for their relatives.

The Randomized Clinical Trial (RCT) will be conducted following the guidelines of the Consolidated Standards of Reporting Trials (CONSORT: http://www.consort-statement.org) and the SPIRIT guidelines (Standard Protocol Items: Recommendations for Intervention Trials). Participants (N=120) will be randomly assigned to two groups (after receiving a diagnosis of Borderline Personality Disorder according to the DSM-5): 1) STEPPS program for patients 2) STEPPS program for patients and Family Connections for their relatives. Participants in the second group may receive the Family Connections intervention for their relatives after completing the research evaluation period for ethical reasons. Outcome measures will be assessed at baseline, post-treatment, and at 6-month follow-ups.