Could this also be read as "he will read to" (all his brothers and sisters) - as in reading a book aloud ?
Yes, but often people would use the verb להקריא to avoid this double meaning.
Would this not be better translated as "he will call to all his brother and sisters"? Without the "to" it seems to mean he will call them on the telephone
הוּא יִקְרָא לְכָל הָאַחִים וְהָאֲחָיוֹת שֶׁלּוֹ