Robot Boy from Ganymede?
Alfonso Bresica/Al Bradley directed several Italian space operas in the late 1970s. It seems rather hard to keep track of which English language titles correspond to which original Italian titles.
In one of them Earth Humans fought off an alien invasion, aided by two Human-looking aliens who came from Ganymede (the asteroid, the Jovian moon, or some extra solar planet?). The little boy alien was revealed to be a robot.
I wondered if War of the Robots was that movie, but yesterday at a site called Scifi-Movies, I found a listing of Battle of the Stars (Battaglie negli spazi stellari) with a synopsis and photos that show that it is the movie that I remember.
I hope that will be a little help for those who have found it as hard as I have to keep track of the movies in the Alfonso Bresica space opera series.