Help with Domain Mask

Cloudflare doesn’t do domain masking. And I’m not exactly sure what you’re trying to do.

You have smglobalshop with stuff.
And it sounds like you want something like smglobalshop/COLLECTION1 to show up as sub.myshop.com

If they’re on the same server, you can do some domain mapping within the server configuration files.

You could try using Workers for this. There’s a recipe exchange, and something like this might work: