Take a look at your cloud DB. I created a new tab on the Facture client DB and created a new formula field with the following code:

'DSA 1'.'N° interne' + " " + 'DSA 1'.'Marque & modéle'.'Marque et modéle DM' + " " +
"N°" +
'DSA 1'.'N° série' +
" " +
'DSA 1'.'Site / service / N° Cde'

Then I added this new formula field to the print layout. It works but is clumsy.

Something that will help in your printing with the old print engine, is to create a new child table of Facture client. You can call it 'éléments de facture' (sorry for the bad google translation). Now Ninox will display the linked records for you in a list in the print layout.

If you find yourself creating fields with the same name and end with a different number, like you do with DSA 1, DSA 2, DSA 3, DSA 4, etc, then you should create a child table. Then that child table has a link to Facture client and to DSA. This way you can create 1 linked record or 10000 linked records.

Also, may I recommend that you merge all of your product (Marque) tables into one. As they all store the same type of data. You can then create a simple choice field that will differentiate between the products.

In the new Marque table will be a new child table called Images. This way you can store 1 image or 1000 images of a particular item.

Something else you may want to consider is to learn how to use the dynamic printing. It is a much better printing system. You can see this example or attached.