I refer you to my daughter, Sarah (Rosen) Garrett, LCSW at her Phoenix Center,

as that is what she does. She helps those children

There may be something in this book:

Jones, A., Jemmott, E. T., Da Breo, H., & Maharaj, P. E. (2016). Treating Child Sexual Abuse in Family, Group and Clinical Settings. Palgrave Macmillan.

You can search for meaningful words; I searched for sand and art and found relevancies although the search for dreams indicated pages that were not free to view:

https://books.google.co.uk/books?hl=en&lr=&id=FrLIDAAAQBAJ&oi=fnd&pg=PR5&ots=4t3li0bnKn&sig=zFioLuKC3uYsVI6eLpYP1mb6AAc#v=snippet&q=sand&f=false

I saw this dissertation, although dreams are not really discussed:

Maharjan, C. L. (2019). Sandplay Therapy for Children with Trauma Living in a Residential Facility in Nepal: A Multiple Case Study (Doctoral dissertation, California Institute of Integral Studies).

https://search.proquest.com/openview/184596c24a9053e2470d189c0f3df074/1?pq-origsite=gscholar&cbl=18750&diss=y

This link mentions sandplay and dreams:

Kowen, M. (2017). A 10-Year-Old Girl’s Overcoming the Negative Mother Complex and Its Relationship to Ego Development. Journal of Symbols & Sandplay Therapy, 8(1), 1-34.

https://www.sandplay.or.kr/img_up/shop_pds/kp645/contents/myboard/01.-gwon-mi-ra.pdf

but references a very old document:

Jung, C. G. (1984).

Archetyp und Unbewustes. Princeton: Bollingen/Princeton University Press.