CBSubs API?

The problem is that we have some plans that need to be exclusive, but there are others that aren't dependent(exclusive) with those.
Also, we need to be able to update one existing plan while adding another.

I can find the old postings here where we went through it, but after over a year of testing and tweaking (and asking questions several times), we've come to the conclusion that CBsubs just can't do what we need to do out-of-the-box, or even with lots of time trying to custom configure.

Don't know what to suggest in that case. We've a CBSubs Options integration planned in a later release that'll allow you to add optional options to a single plan to adjust the price of the plan. That maybe what you're needing, but it's not quite ready yet.