I am working on a class diagram for my internship. I have encountered a situation that I haven’t seen before, and I’m not entirely comfortable with the approach I’ve taken. Here are the relationships I need to model:

in this class diagram I would like to represent the fact that, a spec1 can be associated with class2 once a year to a single instance of class2 or several times in the same year to the same class2 or different instances of class2.
Spec2, on the other hand, can be associated with class2 even several times in the same year with class2 with different instances.