Multiple class options for single end of association

Hi,

This might not be a proper UML strategy, but I have a binary assocation, one end of which can be either one of two classes. So the association is either between class A and B, or A and C. This is not an N-ary assocation, since it’s ‘either or’.

How do I solve this in a class diagram, other than defining the same assocation twice, once between class A and B, and another between A and C?

Thanks in advance.