support for specific where clauses for each relation in the union_relations macro

[thisismath]

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

[github-actions]

This issue has been marked as Stale because it has been open for 180 days with no activity. If you would like the issue to remain open, please comment on the issue or else it will be closed in 7 days.

[github-actions]

Although we are closing this issue as stale, it's not gone forever. Issues can be reopened if there is renewed community interest. Just add a comment to notify the maintainers.