Creating child records from related records

Hi 

Can someone please tell me how to setup a workflow to perform the action below?

Lets say i have 2 entities: Entity A (Template) and Entity B (Entity A is a template for Entity B and there is 1:N relationship)

Entity A has a sub-grid with 5 child items (all child items are templates for child items for Entity B)

Entity B has subgrid with child 5 items (All items are based child items from Entity A)

Please see below

Entity Template A :                                        Entity B (Based on Entity Template A)

Child items displayed in Sub-grid:                    Child items displayed in Sub-grid:                   

LS Template 1                                              LS1 (Based on LS Template 1 from Entity Template A)

LS  Template 2                                             LS2 (Based on LS Template 2 from Entity Template A)

LS  Template 3                                             LS3 (Based on LS Template 3  from Entity Template A)

AP Template 1                                              AP1 (Based on AP Template 1 from  Entity Template A)

AP Template 2                                              AP2 (Based AP Template 2 from  Entity Template A)

Now i need to have a workflow that performs

When Entity B is created, 

go and create LS1, LS2, LS3, AP1 and AP2) from Templates in Entity A. 

How can I set up my workflow to perform this act?

Thank you