How to get from A/B to Proxima?

Although Rama O'Neill can get to Proxima from Earth directly, I'd rather have the craft use that system to brake its delta-V into A/B. Once at A/B, we can look into a return.

In the Alpha Centauri system, Proxima and A/B are (now) 12950 AU apart albeit on approach. Light takes 75 days to travel between them. Here we are asking how much deceleration we can get out of Proxima’s system, from A/B, as 'tis known thus far.

As noted, the planet is 50000 ms^-1 but, the good news, the whole Proxima system is coming toward A/B.

Still, an orbital-insertion from A/B would run only twice as fast as New Horizons at its top speed, and take over an Earth century to arrive at Proxima. Even if Proxima has another decent-sized planet, it might not give a faster craft the delta-V it wants.

Another O'Neill colony-ship will be needed.