method/cover/record override

What is the override order in case of conditional inheritance e.g. struct A: f1, f2 :bool def foo() is ... struct B inherits A (f1 == true): def foo() is only ... struct C inherits A (f2 == true): def foo() is only ...

now let's assume we have A with both f1 and f2 are true - which foo should we invoke/call? same question over cover/record