Need BH Coding. (Ongoing $4u) Payment Gateway etc

Hey,
So I'm not entirely sure of how to explain what I need but I'd be happy to discuss it by phone.
This would involve several websites.
Nothing too crazy on the products, just trying to feed sales in one site through payment system of another without URL's showing another site and without raising any issues with account provider.
I know this is doable but I don't know exactly how to make it all happen.

One site (with a merchant account) will accept payments from another site via redirect/cloaked/not sure/

Ongoing situation, just a little of your expertise in exchange for weekly %

NO BS, nothing weird, just looking for a solution to an ongoing challenge. HMU if you think any of this makes sense and I'll be happy to discuss further. Thank You

Sure, lets discuss it. Pretty good in PHP and APIs and Payment processors so give me a ping if you havent sorted this out yet.