Under the chapter of focus particles (role and position), my grammar book gives two use cases for using auch:
- refers to the whole sentence and is placed before nicht, modal, locative and verb 2 position
Ich konnte meinen Vater gestern dank deiner Hilfe auch pünktlich am Bahnhof abholen.
- Highlights a part of the sentence and is placed just before the part of the sentence highlighted
Ich schenke dir dieses Jahr auch Blumen zum Geburtstag (nicht nur Pralinen).
The first use case where auch refers to the whole sentence confuses me as I am not sure what is the logical scope of auch as „nicht nur“ to cover the whole sentence.
My guess is - Somebody else could pick up their father yesterday punctually at the railway station, thanks to your help. And I too could pick up my father yesterday punctually at the railway station, thanks to your help.
The reason that I am not sure of this, is that it would be then the equivalent of (in my view) :
Auch ich konnte meinen Vater gestern dank deiner Hilfe pünktlich am Bahnhof abholen.
Source: (B2-C1) Grammatik aktiv, Cornelsen 2019, page 24