How Draft invoice lines can group based on Task organization

Hi,

i am using event base billing task organizations are different from each task i want to generate draft invoice separate, where same task Organization (A) are one draft invoice. Another Task Organization is (B)  should generate separate draft invoice how we can group like this.

Task1 Organization is Telangana

Task2 Organization is Mumbai

when we run generate draft invoice it should generate Task1 one draft Invoice. and Task2 is another draft invoice. how we can achieve this. while running draft invoice bot tasks have un invoiced events.

Thanks

Srini