Hello Everyone. I want to create a screen with two Entities inside it(similar to Quote Entry screen can insert product)

e.g : I have Invoice entity and InvoiceDetail entity. InvoiceDetail use for save many items or products in one invoice. So could anybody tell me or guide me some on this ? I'm new to sage crm . I don't know where should i start from or to search.

Best Regards,

/Sokheng