In the Trenches-for speech therapists

I am seeing a 2 year old little boy who has childhood apraxia of speech. Currently he often subs voiced for voiceless consonants. And of course at this age, and with everything else, he reduces consonant clusters.
He walks his sister to school with his Mom everyday and looks for sticks to play with.
So for big stick /BIG STIK/ (in phonetics) with a reduced cluster and voicing for voiceless you get /BIG DIK/.
That error is one that will get 'em into speech therapy every time!