I have a Report for Expenses by Counterparties and Contractors, which looks like the this:
Counterparty 1
- Goods Group 1 Supply Contract: 210
Counterparty 2
- Goods Group 1 Supply Contract: 130

And I would like to have a report looking like that:
Goods Group 1 Supply Contract
- Counterparty 1: 210
- Counterparty 2: 130

How can I implement this? Any ideas? The Data Composition Schema does not want to group contracts and gives the following best result:
Goods Group 1 Supply Contract
- Counterparty 1: 210
Goods Group 1 Supply Contract
- Counterparty 2: 130

It looks like you've named contracts by activites. And want to use them to group those activities. This is bad idea. Contracts represent actual agreements between your company and counterparties. To make the analytics which you want (GROUP BY Activity, Counterparty) you need to add the activity field to your documents and registers and build the report on that field. If it is urgent you can add it to the Contract catalog and use for reports as a first groupping level instead of the contract itself.

I think you have two goods groups with the same name.

can you give reference on the demo-base like this: http://apps.1c-dn.com/1cas/#e1cib/app/Report.BalanceSheet

Unfortunately I can not yet.