Stars Subdomain power: does that mean every spell or just three?

[Reduxist]

The Stars are Right power says you can swap out your stars subdomain spells spontaneously. Does this mean only the three listed can be swapped or can I use any of the spells from the void domain as well?

[Andre Roy]

Well the Void Domain spell for the 1st, 3rd, 4th 5th 6th and 8th remain unchanged when you take the Star Subdomain (and therefor are part of it), so they would be legal options for the spontaneous exchange.

[Cavall]

The stars subdomain includes the remaining void spells. So all of those.

[Agénor]

As they said. The other six spells were not repeated to save effort and space.

I wonder if one could swap a 4th level slot to cast a 3rd level spell in this case.

[Cavall]

"cast any of your Stars subdomain spells by swapping out a spell of an equal spell level."

[Agénor]

Then I wonder why the restriction?

[avr]

I think the stars subdomain spells include those you get from the subdomain via the void domain.