Parenting/social skills groups will be co-led by two therapists and involve 12 group therapy sessions with the parents and their children separately (10 parents and children per group).

Emotion Regulation Checklist (ERC; Shields & Cicchetti, 1997) is a parent-report measure of children's emotion regulation characteristics and involves 24-items rated on a 5-point likert scale (1 = "never" to 5 = "always"). It taps into two factors one of which is emotional lability and negativity defined as arousal, anger dysregulation, and mood changes; and the second is emotion regulation defined as socially appropriate emotional displays, empathy, and emotional selfawareness. The scale has been adapted to Turkish with good reliability and validity (Batum & Yagmurlu, 2007).

The Children's Global Assessment Scale (CGAS; Schaffer et al., 1983) is a numeric scale (from 1 to 100) used by mental health clinicians to rate the global functioning of children under the age of 18 on a scale of 0 to 100. 90-81 range is scored when there is "good functioning in all areas; security in family, school, and with peers with only transient difficulties and everyday worries"; 50-41, when there is "moderate degree of interference in functioning in most social areas or severe impairment of functioning in one area"; and 20-11, when there is "need for considerable supervision to prevent hurting others or self or to maintain personal hygiene or gross impairment in all forms of communication". The scale has been adapted to Turkish with good reliability and validity (Gökler et al., 2004).

Parental Stress Index - Short Form (PSI-SF; Abidin, 1983) is a 36-item parent-report scale.The PSI-SF contains 36 items divided into three subscales, each composed of 12 items: "Parental distress"; "Parent-child dysfunctional interaction"; "Difficult child". Each item is rated on a 5-point likert scale from 1 = "strongly disagree" to 5 = strongly agree". The PSI-SF gives three subscores and a total distress score. The scale has been adapted to Turkish with good reliability and validity (Mert et al., 2008).

Parental Reflective Functioning Questionnaire (PRFQ; Luyten et al. 2017) includes 18 items divided into three subscales that measure PRF. A 7-point likert scale from 1 (strongly disagree) to 7 (strongly agree) is used to score each item. The PRFQ gives three subscales pertaining to "curiosity and interest in mental states", "prementalizing modes" and "certainty about mental states". The scale is in the process of being adapted to Turkish by our research group.

Difficulties in Emotion Regulation Scale (DERS; Gratz & Roemer, 2004) is an instrument measuring emotion regulation problems in adults (to be used with parents in the current study). The scale comprises 36 items that are rated on a 5-point likert scale from 1 = "almost never" to 5 = "almost always", with higher scores indicating a difficulty of emotion regulation. The scale produces scores on the following subscales: (a) lack of awareness of emotional responses; (b) lack of clarity of emotional responses; (c) nonacceptance of emotional responses; (d) limited access to effective strategies; (e) difficulties in controlling impulsive behavior when experiencing negative affect; and (f) difficulties in engaging goal directed behavior when experiencing negative affect as well as a total disregulation score. The scale has been adapted to Turkish with good reliability and validity (Yiğit & Güzey-Yiğit, 2017).

Schedule for Affective Disorders and Schizophrenia for School Aged Children (6-18 Years) (K-SADS-PL DSM 5; Kaufman et al., 2016) is a semi-structured interview that probes child psychiatric disorders according to DSM-5 criteria. If a primary symptom is endorsed, further questions are asked to determine whether diagnostic criteria are met. In the study, specific components of the instrument will be selected to screen for psychosis, autistic spectrum disorders, substance abuse and dependence, acute risk of harm to self and others. It was adapted to Turkish by Ünal et al. (2019).

Kaufman Brief Intelligence Test-Second Edition (KBIT-2, Kaufman & Kaufman, 1990) will be used to screen for general intelligence in children and their parents. The Verbal Scale contains two kinds of items-Verbal Knowledge and Riddles-both of which assess crystallized ability.The Nonverbal Scale includes a Matrices subtest that assesses fluid thinking-the ability to solve new problems by perceiving relationships and completing analogies. The KBIT-2 provides Verbal and Nonverbal Scores, plus a composite IQ. The scale was adapted to Turkish with good reliability and validity (Savasan, 2006).

BAPIRT Alcohol and Drug Questionnaire (Ogel et al., 2017) is a risk-screening questionnaire appropriate for Turkish cultural characteristics in detection of alcohol- and drug-use level through utilization of Addiction Profile Index (API). BAPİRT-alcohol and BAPİRT-drug subscales each involve 6 questions rated on a 3 point likert scale (0 = "none", 1 = "often", 2= "very frequently"). The scale was constructed for use in the Turkish culture by Öğel et al. (2017).

In order to measure parents' and children's early trauma history, an adapted version of the Adverse Childhood Experiences (ACE) questionnaire (Dube et al., 2003; Murphy et al., 2007) will be used. ACE is a parent-report scale and assesses retrospectively forms of abuse, neglect, and household dysfunction (i.e., witnessing domestic violence, separation and mental illness in the family) both for the parent's and child's early history. Scores range from 0-10 on the ACE, with the latter representing full exposure at some point in the first 18 years of life, to all forms of household dysfunction and abuse detailed in the questionnaire. The scale has been adapted to Turkish by Gunduz et al. (2018).

An adapted version of the Attachment Doll Story Completion Task (ASCT; Bretherton et al., 1990) will be used to assess the quality and the security of attachment-related representations of children's relationships with their caregivers. ASCT was originally designed for three-year-olds and later adapted to school age children by Granot and Mayseless (2001). ASCT comprises of five storystems that aim to elicit stories from children on attachment-related day-to-day issues. A set of family figure dolls and related props are used to prime children and invite them to complete unfinished stories. Children are classified as secure, fairly secure or insecure based on their responses. The scale was adapted to Turkish by Uluç (2005).

The Kerns Security Scale (KSS; Kerns et al., 1996) will be used to assess children's baseline attachment security. KSS is a child-report scale and comprises of 15 items measuring (a) the extent to which children believe that their attachment figures are sensitive and available; (b) their tendency to trust attachment figures under stress; and (c) their level of willingness to communicate with attachment figures. Children complete the form separately from both their mother and fathers. The items are rated on a 4-point likert scale "Some kids . . . Other kids. . ." format with higher scores indicating a more secure attachment. The scale was adapted to Turkish by Sümer and Anafarta-Şendağ (2009).

Experiences in Close Relationships Scale-II (ECR-II; Fraley et al., 2000) will be used to assess the attachment patterns of the parents at baseline. The ECR-II consists of a total of 36 items, 18 in the anxiety and 18 in the avoidance sub-dimensions. The items are answered on a 7-point likert scale (1= "Never Agree", 7= "Strongly Agree"). The scores for each attachment dimension are calculated by taking the average of the item total score. The increase in scores indicates an increase in the anxious or avoidant attachment patterns. The adaptation study of the ECR-II Turkish Form was conducted by Selcuk et al. (2005).

The Child Attachment Interview (CAI; Target et al. 2003) is a 19-question, semi-structured interview for 8- to 12-year-olds that assesses children's attachment representations of their current relationships with their primary caregivers. CAI coders rate videotapes and verbatim transcripts on 11 9-point scales (e.g., idealization of attachment figures, balance of positive/negative references to attachment figures).

The Experience of Service Questionnaire (ESQ, Brown et al., 2014) consists of 12 items rated on a 3-point likert scale (1 = "not true"; 3 = "certainly true") and 3 free text sections looking at what the respondent liked about the service, what they felt needed improving, and any other comments.

The Therapeutic Alliance Scale for Children-revised (TASC-r, Shirk et al., 2011) will be used as a measure of therapeutic alliance across treatment. The TASC is a 12-item, 4-point Likert-type scale completed by the children and parents and there is a parallel version for the therapist to complete. Each item is rated on a 4 point scale ranging from 1 = "not at all" to 4 = "very much". The scale will be administered to patients in the MBT-C arm.