Renewing subscriptions without losing machines

So, I have a problem. In the past, we were using subscriptions incorrectly. We were using our Satellite subscription for everything even though we did not then have a Satellite instance. Even though we were doing things incorrectly, there was no problem with the finance because we were paying for everything so technically, we were ok. I only mention this so that yyou understand when it came time to renew our Premium and standard subscriptions, I had to go register each machine to one of the valid subscriptions from scratch.
When we did that, it did not seem as though auto-attach was working so we were told to use the pool-id. That seemed to work fine. Fast forward a couple of months and we build a satellite server, supply it with entitlements via a manifest and adopt SCA (Simple Content Access)
So here is my problem. Since I have never renewed subscriptions that were in proper use, I don’t know how to go about doing that. Our renewal is through a 3rd party vendor. We have added 8 premium and 3 standard subscriptions. But as of now I have no idea how we are supposed to effect or activate the renewal. I am very concerned that for the machines that we still have pointed to CDN we are going to have to re-register and re-attach to a subscription. And I have no idea what is going to happen to the manifest that we use to feed the satellite server. There has to be a simple way of renewing subs without losing all of your attachments, especially when we were told to use the pool-id. And even though we do not do to much wth Satellite now we do use it enough that re-registering of 75 machines would be painful.
I can’t seem to find an answer for this, so I am hoping that someone out there has a solution. Maybe a step by step set of instructions or a pointer to a concise document