My understanding of Spanish grammar from studying Spinelli and Kendris’ 500 Spanish Verbs is that the subjunctive mood is required when 1) the subject changes between clauses and 2) one of the clauses contains an expression that is contrary-to-fact. There are other reasons that require the subjunctive but my questions concern the two reasons I’ve stated.
This English sentence,
“There is nothing in that report that I had not already known.”
I believe, can be expressed in Spanish in either of these two ways:
«No hay nada en ese informe que no había supiera ya.»
«No hay nada en ese informe que no había sabido ya.»
In these examples, No hay nada is contrary to fact and nada, the subject of the first clause is different from the implied subject, yo, of the second. Thus, one might say there are two reasons to use the subjunctive.
The first Spanish sentence uses the imperfect subjunctive of saber with the past perfect indicative of haber, while the second uses that same auxiliary verb with the past participle of saber.
With only supiera, as in:
«No hay nada en ese informe que no supiera ya.»
Which I believe in English is:
“There is nothing in that report that I did not already know.”
There doesn’t seem to me to be any difference in the two English sentences as to nothing in the report was unknown to the speaker before he examined the report, or said another way, he knew everything that was in the report before he read it, but perhaps there are subtle differences in the three Spanish versions? Which is correct, and why? Or, perhaps none is correct, and if so, how are these English sentences best expressed in Spanish?