How to subclass a family

[Antoon Pardon]

Here is the idea. I have a number of classes with the same interface.
Something like the following:

class Foo1:
    def bar(self, ...):
        work
    def boo(self, ...):
        do something
        self.bar(...)

What I want is the equivallent of:

class Far1(Foo1):
    def boo(self, ...)
        do something different
        if whatever:
            self.bar(...)
        else:
            Foo1.boo(self, ...)

Now of course I could subclass every class from the original family
from Foo1 to Foon but that would mean a lot of duplicated code. Is
there a way to reduce the use of duplicated code in such circumstances?

-- 
Antoon Pardon