Feature summary :
Select and edit a specific instance of a template in a page that contains several instances. Today this is possible with autoedit but not with a standard form. With a standard form, all instances are necessarily displayed in the form.
To select the desired instance, it could be possible to use its rank in the page (as is already the case when you want to modify a specific instance with autoedit) but also with query criteria.

This feature is close to T274672.

Use case(s)
Let's take the example of a page that contains a recipe. Each ingredient is a sub-object that is defined by the type of ingredient and its quantity.
It would be possible to display on the page as many #formlinks as sub-objects, and each of them could allow you to modify for example the quantity of the corresponding ingredient, without all the ingredients being visible in the form.