Hello - I have no experience of this, but it occurs to me that without caution, you may be seen as yet another abusing adult. Somehow, if children are to heal from their experiences they need to experience you as supportive, non-coercive beyond where they are willing to go with you. This would be so for any client, and it may mean taking more time to build trust, and a relationship where the children feel that they would want to talk with you. I think sometimes Gestalt techniques can be a bit brutal.
with best wishes