Hello,
in the CRM environment - so in the SolMan as well - you can make use of CL_CRM_DOCUMENTS. Using method CL_CRM_DOCUMENTS=>CHANGE_PROPERTIES you should be able to change the file name.
You will find further information about the API in the following SAP note:
632877 - CRM Content Management: API for document management
Is this what you are looking for?
best regards,
Johannes