Describe the feature

currently the union_relations macro uses the provided where clause for all relations passed to it. In some cases, this approach is not ideal. Support for specific where clauses for each relation would allow for more flexibility in the way the macro can be deployed

Describe alternatives you've considered

CTEs would be an alternative but union_relations only takes models as inputs

Who will this benefit?

An example use case: Supports unioning differing periods together

Are you interested in contributing this feature?

sure