Well that should be dictated by the WSDL. How many operations does it support? If it doesn't support all the operations then you need to add additional SOAP services using a new WSDL with the operations you need.
To check this, find your SOAP service in the services tree in the bottom left hand corner of Policy Manager. Right click the service, and choose Service Properties. From here, click on the WSDL tab, and you should see the WSDL and any operations supported by it. If you need further assistance you can click the button "Edit WSDL", and a dialogue window appears. Click Next once, so that you are at the "2. Compose WSDL" section and you should also see what operations are supported in the "Resulting WSDL" section. You can cancel this window once you know the operations supported.
Although not reccomended, you can also allow operations not contained in the WSDL by checking the box on Service Properties for the API, under the WSDL tab. The checkbox is labelled "Allow requests intended for operations not supported by the WSDL". I would only use this to temporarily troubleshoot any WSDL issues as this opens a security issue for your API.