You're right it works! Just don't give me an error when I delete the sales order line ... could you tell me why?

Uncaught Error: QWeb2 - template['ListView.rows']: Runtime Error: Error: QWeb2 - template['ListView.row']: Runtime Error: Error: NameError: name 'promo_block' is not defined

Have you added any new field with name promo_block?

Yes!

record id="sale_promotion_in_sale_order_form" model="ir.ui.view">

<field name="name">sale.order.form.add.promotions</field>

<field name="model">sale.order</field>

<field name="inherit_id" ref="sale.view_order_form" />

<field name="arch" type="xml">

<xpath expr="//field[@name='order_line']/tree//field[@name='price_subtotal']"

position="after">

<field name="promo_block" invisible="1"/>

<field name="promotion_code" readonly="1"/>

</xpath>

<xpath expr="/form/sheet/notebook/page/field[@name='order_line']/tree" position="attributes">

<attribute name="decoration-muted">promo_block</attribute>

</xpath>

</field>

</record>

I think error with the follow line

<xpath expr="/form/sheet/notebook/page/field[@name='order_line']/tree" position="attributes">

<attribute name="decoration-muted">promo_block</attribute>

</xpath>

I have deleted

<xpath expr="/form/sheet/notebook/page/field[@name='order_line']/tree" position="attributes">

<attribute name="decoration-muted">promo_block</attribute>

</xpath>

but I've this error:

Uncaught Error: Unknown field qty_invoiced in domain ["|",["qty_invoiced",">",0],["procurement_ids","!=",[]]]

have you ever found it?