To link your inventory and invoices to e-way bills generated in BUSY, you need to ensure that the inventory items are properly linked to the invoices. This can be done by selecting the relevant inventory items while creating the invoices in BUSY. Once the invoices are generated, you can then generate the e-way bills by providing the necessary details such as the invoice number, transporter details, and vehicle information. The e-way bills will be automatically linked to the respective invoices in BUSY.