"However, only with your support can [Subject] respond to ..."

[Odessa Dawn]

When "not only" starts the sentence, the subject and verb that follow are reversed.
More: https://www.usingenglish.com/forum/ask-teacher/172379-how-use-not-only-but-also-could.html

The rule is not that random. Whenever you have a negative phrase start your sentence, you invert.

Scarcely had I started when...
Never will you find...
Rarely had he seen...
Not only is this...
More: https://www.usingenglish.com/forum/ask-teacher/172379-how-use-not-only-but-also-could.html

"The world's needs grow greater every day and God is opening many doors of opportunity here at home and around the globe. However, only with your support can [Subject] respond to these hurting people."


We don’t have the adverb not before the focusing word only. So, Why did the subject and verb get reversed? Is the word not optional? I came across a lot of texts where the word also can be omitted. (Not only…., but … ) without also.

P.S.: I have concealed name intentionally. It might be used for advertisement.
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[SoothingDave]

This is not the same situation and the word "not" is not optional here. It was "omitted" on purpose.

 

[5jj]

'Only when' can be interpreted as ' 'on no occasions except when'.