Is this coin going to fork from ZCl or from BTC? If the plan is to fork from ZCL, then I guess BTC owners will have to use sign/verify message as a mechanism for claiming, right? Be aware that this mechanism is not defined for segwit type addresses, which basically leaves out everyone who moved to segwit.
ZCL and BTC both included.
You own 1 ZCL --> You keep 1 ZCL + get 1 BTCP
You own 1 BTC --> You keep 1 BTC + get 1 BTCP
And yes, BTCP does not have SegWit hence the fork will leave out all SegWit BTC addresses.