Not only negative A but on the contrary B

Question

Not only does she not support this plan, but, on the contrary, (she?) tries to prevent it.

Not only will the change not deteriorate the conditions, but, on the contrary, (it?) will improve them.

Not only do boosters not reduce speed, on the contrary, (they) increase it.

1. Where to place not in the above sentences?
2. Is the subject (she, it) in the second part of the sentence necessary?
3. Regular clause goes like "Not only .. but also". But here also sounds awkward since it somehow should go in pair with a positive.

Answer 1

The term "on the contrary", which means 'the opposite', does not work in these example sentences because they all begin with "not only", which implies you are going to tell us two things when in fact you're only telling us one thing, two different ways.

Not only does she not support this plan, but, on the contrary, she tries to prevent it.

You need to either choose to use 'not only' or 'on the contrary' and structure the sentences like this:

• Not only does she not support this plan, but she tries to prevent it.
  or
• She does not support this plan; on the contrary, she tries to prevent it.