task group assignment 

when you create a task either you can select assigne from the list or click on select/deselect all to select all the members from the list after that they all would be listed with their names in the checked boxes you can deselect any one of them you donot want (part remaining here is to sort them in proper order)
after click on save u can see in all task multiple task with the same name(working on giving them different colour for differentiation and finally showing them under one collection).

update for the task contaning collection of task is stoped<---(temprory)
working on Assignig different colours to task according to their status