Hi,

The sequence number is generated when we save a record. You can check the sale.py file inside the sale module.

Below is the code which generates the sequence number for sale order,

As you want to add the customer name along with the sequence, you can change the above code like this,

Just add a the selected two lines to the code.

partner = self.env['res.partner'].browse(vals.get('partner_id'))
vals['name'] = str(vals['name']) + str(partner.name)

Either you can do it editing the original code or a custom module.

Thanks