Is it possible to do a custom object nested query on a standard object?
[SELECT (SELECT Id, Case__c FROM Accounting_Instructions__c WHERE Accounting_Complete__c = TRUE AND Case__r.Id =:currentPageId), AccountId, CaseNumber FROM Case WHERE AccountId = :strAccountId AND Id IN :accountIds];
There is a relationship between Accounting_Instructions__c and Case (similar to Task and Case). I know you can do two standard objects and use the relationship name. An example of this is in this post: Query of Tasks for Custom Object.
Because of this format my initial thought would be to change
Accounting_Instructions (like Task to Tasks) but this doesn't make sense because it's a custom object so I have no idea how Salesforce would understand this naming convention.
All of the documentation I am finding is examples of standard to standard object or custom to custom objects. Any advice?