flectra/addons/account_voucher/security/account_voucher_security.xml

<?xml version="1.0" encoding="utf-8"?>
<flectra>
    <data noupdate="1">
        <record id="voucher_comp_rule" model="ir.rule">
            <field name="name">Voucher multi-company</field>
            <field name="model_id" ref="model_account_voucher"/>
            <field eval="True" name="global"/>
            <field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
        </record>
        <record id="voucher_line_comp_rule" model="ir.rule">
            <field name="name">Voucher Line multi-company</field>
            <field name="model_id" ref="model_account_voucher_line"/>
            <field eval="True" name="global"/>
            <field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
        </record>
    </data>
</flectra>