After I open the one-page Checkout plugin, I modify the jump page modification in checkout_shipping and it doesn't work.

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Can the plugin control the page that jumps?
I just want to click the checkout button on the shopping cart page, the customer will jump directly to the registration page if they are not logged in.
Close the one-page Checkout payment plug-in to modify the judgment of the above screenshot to achieve my idea, but after opening one-page Checkout plug-in, skip to the login page.
Can the plugin directly control the jump page? Which file code do I need to modify?