1. Place the cursor on the left parenthesis of the form (same as you wrote)
2. C-M-Space to select the form.
3. M-( to surrond with parenthesis.
4. type "if flag" (same as you wrote for #3)
One extra step, but no need for a plugin.
Also, I added a simple "insert-quotes" that I think I mostly copy-pasted from the built-in "insert-parentheses":
(defun insert-quotes (&optional arg) (interactive "P") (insert-pair arg ?\" ?\"))
That's M-" .
1. Place the cursor on the left parenthesis of the form (same as you wrote)
2. C-M-Space to select the form.
3. M-( to surrond with parenthesis.
4. type "if flag" (same as you wrote for #3)
One extra step, but no need for a plugin.
Also, I added a simple "insert-quotes" that I think I mostly copy-pasted from the built-in "insert-parentheses":
So I can replace my #3 above to wrap something with quotes instead of parentheses.