Determining the set of entities that’d have to agree to discard a subgraph means correlating node activity logs. Corda nodes log sufficient information to ensure this correlation can take place. The platform defines a flow to assist with this, which can be used by anyone. A tool is provided that generates an “investigation request” and sends it to a seed node. The flow signals to the node administrator that a decision is required, and sufficient information is transmitted to the node to try and convince the administrator to take part (e.g. a signed court order).