Is there a possibility to combine a posting line from the bank to a member (donor) in the CiviCRM database? More precise: Could we load the bank statement to CiviCRM or is it necessary to put every donation manually to the donor?
There is an extension CiviBanking that allows the import of bank statements. The extension can be found here:https://github.com/Project60/org.project60.banking
Whereabouts are you located? The extension is currently used by a couple of European organizations.
You can do a contribution import through the standard contribution import process, but you will need to ensure that the bank statement is in the proper format (1 line per contribution) and exclude any other transactions.
What generally makes this difficult is the dedupe rule - how can you identify the contact on the bank statement. You probably want to create a special dedupe rule for this.
Do you have a way to match the contact record?