Thanks Pablo for hints.
I will ask to a more tech than me person to implement it.

I see that below  And you need to add this line....  there is big empty space. 
The same below  And modify the t-foreach.
Did you miss something ? Did you write some code or an image ?

Hi, 

I have the same problem and it can be solved in the following way:

1º Create new integer field in model product.template in me case with studio (EJ -> x_studio_optional_priority_products)

2º Assing priority to products or variant products.

3º You need to inherit the view and modify in me case the view are optional_product_item

And you need to add this line 

LOOK COMMENTS

is for order the items by priority

And modify the t-foreach.

Thats the unique solution I found.