Some degree of "IMO" here, but in C++, multiple inheritance is generally an indicator of flawed design. Don't attempt to transliterate Python idioms to C++. The solution domains are sufficiently ...

Simple, object oriented, and familiar; Robust and secure; Architecture neutral and portable; High performance; Interpreted, threaded, and dynamic; The reasons for omitting multiple inheritance ...

With multiple inheritance you might be tempted to say the Pegasus extends Horse and Bird because you've classified the Bird as an animal with wings. However, Birds have other traits that Pegasi don't.