I have a question regarding payment options. When a user clicks on checkout and proceed on the payment page, can this request be redirected to another Shopify site? On this site a user should fill-in the form and pay. Both Shopify shops are identical.
If there is a programming to do, we could pay for it.
This isn’t something that can be easily enabled within Shopify, nor is it something we’d be able to support directly. It may be possible to have a redirect set up when you proceed from the cart page to checkout, but this is theoretical. You’d be best served hiring a Shopify Expert who specializes in web development and asking them if this is something that can be done.