All correct, but for the record, and since the sourced file is env.ksh - smells like setting up the environment? - one could also, if so inclined, stuff functions into environment variables, since those are propagated:

qwurx [shmem] ~ > env BLORF='blorf () {
echo $* blorf.
};' sh -c 'IFS=" "; eval $BLORF; BLORF=""; blorf I say'
I say blorf.
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;-)