The usage is most important. Please note that according to the Indian Trade Mark Act, Registration of Trade mark is not compulssory for a claim on the mark. . The evidences of first usage(user) is most importatnt. Regarding the Regd user, the most important practical right is the right to file a suit at the jurisdiction of the regd. owner.
There is no strict barring in the usage of surnames, though some are not objectionable.
Regarding case details, you are requested to raise the exact questions. A number of cases are available. First u ple. go through the Act and put the exact situation of case.
The question is very interesting. Thanks.