Finding truly co-occurring competent residential treatment programs for young adults is a large challenge. Few programs have the required expertise. Fewer still have the needed quality of service. It is rare that there is insurance coverage and the cost of treatment is quite high.
For residents of Fairfax County, Virginia there may be options not open to residents in other parts of the state. https://www.fairfaxcounty.gov/community-services-board/services/residential-treatment
It might be worth checking out the Newport Institute, which does have a program in Virginia, https://www.newportinstitute.com/programs/residential/ I am not familiar with this organmization as they started after I retired from mental health services in Virginia. They are accredited by the Joint Commission.
Checking programs under consideration for accreditation is a good idea. The three main accrediting organizations for behavioral health programs are the Joint Commission, CARF, and COA. Accreditation is not a guarantee, but does indicate a certain level of quality. This can be helpful when considering programs that are unknown.
Hope you are able to find a suitable placement for your client.
