Hi
Thanks to take care of me 
In my blueprints folder, i have a gallery.yaml which imports the fields related to the gallery:
import@1: type: partials/gallery context: theme://blueprints
Not important in this explanation, in my blueprints\modular folder i have a gallery.yaml which import the fields related to the gallery
For my blog, i have also the item.yaml which imports the blog-fields.
Instead of using item.yaml, i can use also the first gallery.yaml where i would like to insert the blog-fields only when the parent is a blog.
I don’t want to see the blog-field outside a blog and i don’t want to create a itemgallery.yaml for maintenance reason.
At each time i need a new parameter for the gallery, i add it in only one yaml.
At each time i need a new parameter for the blogitem, i add it in only one yaml.
Mick