There is no way to add or modify Business Service (from CMDB) association with Change or Incident. 'Manage Related Configuration Items' Process Action that is meant for creating Process References to CMDB items only works with Assets but not with Services.
A Business Service can currently only be associated with Incident or Change in respective feeders:
The project behind 'Manage Related Configuration Items' (SD.AssetViewProject) does not currently contain logic to add or modify Business Service assocations.
This is currently in a closed project that cannot be customized.
This issue is resolved in ServiceDesk 8.5 and newer.