Hi Remya,

You can just go to: Settings / Technical / Sequences & Identifiers / Sequences / sale.order , and you can create separate sequences for each company (duplicate existing sequence and create one for each company).

See also the answer from:  https://www.odoo.com/forum/help-1/question/configuration-on-odoo-v-13-multi-company-setup-158830#answer-158840

BR

Ricardo

Hi bro,

To do that you need first to create 3 sequences and define their names and prefix.

Then add this code in your class : 

@api.model
def create(self,vals):
	if self.company_id and vals.get('name', '/') == '/':
		if self.company_id.name =="YourFirstCompanyName":#Company1 
			seq_id = self.pool.get('ir.model.data').get_object_reference(self._cr,self._uid,'sale_order', 'YourCompany1SequenceID')[1]
			self.name = self.pool.get('ir.sequence').get_id(self._cr,self._uid , seq_id, 'id',self._context)

		if self.company_id.name =="YourSecondCompanyName":#Company2
			seq_id = self.pool.get('ir.model.data').get_object_reference(self._cr,self._uid,'sale_order', 'YourCompany2SequenceID')[1]
			self.name = self.pool.get('ir.sequence').get_id(self._cr,self._uid , seq_id, 'id',self._context)

		if self.company_id.name =="YourThirdCompanyName":#Company3
			seq_id = self.pool.get('ir.model.data').get_object_reference(self._cr,self._uid,'sale_order', 'YourCompany3SequenceID')[1]
			self.name = self.pool.get('ir.sequence').get_id(self._cr,self._uid , seq_id, 'id',self._context)
	return super(sale_order, self).create(vals)

YourCompany3SequenceID = xml ID of the  sequence for the third company. 
Dont forget to vote positif :)