As far as S1
Isnt it really an S2?
The mom plant being selfed was the first generation and then your selfing it, making a 2nd generation of that line.
So, wouldn’t S1 be a misnomer?
Yes If the mother is a selfed plant, the plant in questions would be a S2 
Sry for a late answer.
Pz 
If the mom is an F1 (or any fgen) and you reverse a clone to the female, offspring are technically F2
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If say, you have multiple F1 plants and you find 2 keeper females, using STS to pollenate one to the other would produce F2 fem seeds and they would act like F2 reg but without the males.
Pz
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