sounds like it. Add this print(get_parent())
to _ready()
It will tell you the parent.
It depends what you want to do, but you could add all of the instances to a a group, such as: add_to_group("nmeships")
Which is what I do for all of my enemy ships. Then to get all of my enemy ships, I do:
var _nmeships = get_tree().get_nodes_in_group("nmeships")
And to loop through them: for _enenmy in _nmeships: