In employee there is field name as address_home_id (Private Address). If you fill partner in private address then same partner will update in salary account entries.

You have to create a contribution Registers from employees without link it to any partner and for employee, you have to set the private address to related partner and in the employee partner, you have to set the account receivable and payable.

The below is the method in hr_payroll_account module which return the partner id, please check it with your configuration:

def _get_partner_id(self, credit_account):
    """
    Get partner_id of slip line to use in account_move_line
    """
    # use partner of salary rule or fallback on employee's address
    register_partner_id = self.salary_rule_id.register_id.partner_id
    partner_id = register_partner_id.id or self.slip_id.employee_id.address_home_id.id
    if credit_account:
        if register_partner_id or self.salary_rule_id.account_credit.internal_type in ('receivable', 'payable'):
            return partner_id
    else:
        if register_partner_id or self.salary_rule_id.account_debit.internal_type in ('receivable', 'payable'):
            return partner_id
    return False