merge derived classes

[nc90]

i have a design that was implemented with a base class A and derived classes B and C. now i want to merge all this functionality into one class.

approaches suggested so far:

derive a class D from A and add code for merge

derive a class D from either B or C and add additional functionality

any other suggestions? i cannot use A because of some upgrade issues.

[helios]

Multiple inheritance?

[nc90]

sorry should have mentioned..anything other than multiple inheritance

[moorecm]

Additionally, you'd have to watch out for the diamond problem with multiple inheritance.

Could you just create a class D and use composition?