cannot and must not

There is a Mandarin word shi3bu5de5 使不得 which means must not (do something) or cannot be used and how do we say this in Teochew Uê?

I have this trilingual dictionary which translate Mandarin into Teochew, Cantonese and Hakka and shi3bu5de5 使不得 is not included and similarly this word is not listed in Mogher.

Shi3bu5de5 is said by some Teochew people outside our homeland as bhoi6sai2 and by Teochew people in our homeland as mo2.

bhoi6sai2	𠁞使｜𠀾使
mo2	孬

Just like bhoi6sai2, bhoi6dig4 is not used by our people in our homeland.

bhoi6dig4

𠁞得｜𠀾得

Bhoi6dig4 is said in Mandarin as bu4de2 不得 or bu4neng2 不能 and has a similar meaning to bhoi6sai2.

Perhaps readers from China could explain to us why our people in our homeland do not use the words bhoi6sai2 and bhoi6dig4 and say mo2 instead. I am not implying that Teochew people living outside our homeland do not use the word mo2.