Kenya Shilling currency and gateway


I am in Kenya and we only use the Kenya Shilling currency. I have two questions:

1. We know how to make a gateway for our local payment processor, and we did make one. However, after updating Membership plugin just now, our gateway disappeared! How do we make it persist through Membership plugin updates?

2. How do I add KSH as a currency and that, too, persists across Membership plugin updates?