I’m not sure of the grammatical order in this scentence
I have learned about" Sentence topic, Time, Location, Subject, Indirect object, Direct object, Verb"
“学校から私に家へ手紙を送った”
Is “家へ手紙を” describing a direct object or is it something else ?"
I haven’t learned all the kanji yet in the scentence and only know some of them
This scentence is from the sakubi grammer guide: https://sakubi.neocities.org/#moving
手紙 is the direct object. 家 is the place it was sent to, so I suppose that counts as an indirect object. Sentence order for Japanese is very flexible (although the verb must always come last), so I wouldn’t worry too much about memorizing any particular order beyond Subject-Object-Verb.
Edit: I took a look at the source you gave, and I think you should probably disregard this sentence pattern. It’s clear from the purpose of the lesson that they were purposefully trying to shoehorn から, へ, and に into single sentence. I don’t think it sounds particularly natural.
Fyi its spelled “sentence”
I didn’t even realise I made that typo