Here is screenshot The main thing I wanted to do is "Free Trial" product.
To do this, I created new original product as $3 ($3 is only shopping fee). When customers click "start with a free trial" I return the variant of this $3 product based on the subscription product variant ID (as per size of subscription product). In other words, I select size for the subscription product, and I click trial, then I return variant ID based on this subscription product's variant ID.
I also set the workflow for recharge. Here I did the reverse of above action. I return the subscription product's ID in this workflow.
But when I purchase free trial product it doesn't continue to subscription. Subscription has been automatically cancelled.
I'm not sure why. So please let me know if someone knows the best way to implement "Free Trial" product for current condition. Looking forward to favorable reply. Regards.