Select component instances within groups and make unique

If I select instances of a component when they are all in the same group level, I can right click and make them unique and they will all become instances of a new component.
How can I do the same when the instances are within nested groups?

It should be the same procedure. But there need to be more than one instance of the component in the model, i.e. in the editing context plus other contexts together.

I should mention that I can’t select these instances normally, since opening a group removes selections. So I use an extension (selection toys) that allows to select. But then right click doesn’t give me ‘make unique’

Well, you should have mentioned that you want to do an operation on more than one instance in different levels. You can’t with native tools. You simply can’t select geometry in different levels to operate on.
You could however do the ‘Make Unique’ operation on instances in one context and then do a ‘Replace’ operation on the selected instances in another (editing) context, replacing them with the unique component. Thus two steps or that many steps as there are contexts that need replacing instances.

If you select all instances in different contexts with the selection toys and you would be able to click on “make unique”, they would be new copies of the same component definition again and nothing would have been changed?! (Or are you able to select only some instances within different contexts with the plugin (I don’t think so)?)

I can select all and then deselect some