Code refactoring. Classes implementing same Interface

I have 4 Classes which Implement the same Interface. The Classes are e.g

ABC, XYZ, LMN, now the Instance of class LMN may belongTo the instance of XYZ means can also be a Child Object. And If a Object is a child obect then It should not have all the methods available as independet object, Or there will be slight difference in it's functionality.

What is generally the best Pratice to handle such kind of sitution.