the usage of as if/ as though

It doesn't work as it is. You could say "They decided to raise him as though he were a normal child".

But I have seen this sentence in an English textbook before. As if she were a mute, she hasn't said a word for some time.
Can you explain the difference of two sentences?
Thanks a lot

As though he were a normal child, they decided to raise him.

I see the above sentence is grammatically incorrect.
Can you tell me why it is incorrect?

Here is another question.
In high school textbooks I have found some sentences like this ; As if he were a normal child, he decided to raise him.

I want to know why it is grammatically correct.

thanks in a

AnonymousAs if she were a mute, she hasn't said a word for some time.

I think this sentence is awkward, but acceptable. It refers to the same person and the same characteristic in both parts of the sentence, and the meaning is clear.
The original sentence has two possible meanings.
a) They decided to raise him in the same way they would have if he were