In theory, the Mini International Neuropsychiatric Interview (MINI) Kid could be used for this purpose. It was not designed for those with intellectual disabilities, but the wording is more simplistic than is used in the regular version. In the MINI Kid there is a version specific for the child that is usually clinician-rated, which could be asked to the person with the intellectual disability, and a version specific for the parent, which could be used (depending upon the severity of the intellectual disability) to ask the person's caregiver (if appropriate). It is possible the language on the interview might need to be slightly modified for this use. The MINI Kid 6.0 is currently out and maps to DSM-IV and ICD-10 psychiatric disorders. The MINI Kid 7.0 will be completed soon and it will map to DSM-5. The MINI Kid 7.0 will contain an adapted version of the 3 linguistically validated pediatric versions of the Sheehan-Suicidality Tracking Scale. See the following link for more information about the MINI and MINI Kid 6.0.
I'm sure it could be translated into Portuguese if necessary.
PAS-ADD family is the best. In two stage design it can be used for screening and detailed evaluation. It is backed by reliability data and can generate diagnoses for ICD as well as DSM.
The Portuguese Ministry of Health will fund this project, aimed at identifying individuals with mental disorder and intelectual disability in the Portuguese population. Therefore, it will be a population-based study, including all age-ranges, and all grades of intelectual disability. I thought that the best way would be to do a two stage design with a screening phase, followed by a more detailed evaluation. Since I am not aware of an instrument translated for Portuguese, first of all we would have to choose an instrument, and then translate it.
The Developmental Behaviour Checklist (DBC) is translated to Portuguese and validated for people with ID. It's carer report so not too labour-intensive.