Or vs Otherwise?

In the sentence, "Indian parents should not coerce adolescents to follow their decisions otherwise they will revolt." we are told that the adolescents will revolt should the parents coerce the adolescents to follow decisions made by the parents. I submit for your consideration that both the words "or", and "otherwise", should be excluded. Perhaps "Indian parents should not coerce adolescents to obey them, as revolt will ensue." communicates the ideas to your liking.

Indian parents should not coerce adolescents to follow their decisions otherwise they will revolt.

Indian parents should not coerce adolescents to follow their decision or they will revolt.

First, the ‘sentence’, as it stands can only be a stretch of conversation or oral debate. If it were from a written text, then it is one which leaves much unexpressed to be assumed. It is also, in that case, badly punctuated. Despite this , however, the meanings are completely clear and has to be the same, whether the word ‘or’ is used or the word ‘otherwise’.

The words otherwise and or have similarity and difference. Their logic - what they do in any sentence - is very similar. But otherwise functions both as a conjunction and as an adverb, (for example Cambridge lists it in that way) while or is just a conjunction (or, more strictly, a disjunction. It defines otherwise as follows:-

used after an order or suggestion to show what the result will be if you do not follow that order or suggestion.

The examples it provides all separate the two clauses with comma, not the colon I prefer.

Merriam takes broadly the same line as Cambridge, differently expressed, of course. It agrees with Cambridge in using a comma before otherwise in its examples. On that basis, it is safe to say that a comma is preferred on both sides of the Atlantic (and probably in India too.

So, both versions could do with a comma, but both are standard English usage.