I have a case where the base class A is parent of many other classes, it's a domain model base class with some common behaviour, and I can't change it by adding validation groups.

I can't add validation group, because of this changement imposes a very large refactor on my code base, that I can't do.

Moreover base class A has other validation constraints that I would use as is in the base class validation.

Summarizing I would like to maintain the base behaviour in majority of cases, but in some specific cases I would like to add a very specific constraint.

I wonder, maybe I'm wrong and I should have used validation groups from the beginning, but the requirement has emerged too late.