i need to understand something here ..

how come the Main Dev Team of Bitcoin Core apply segwit ?  where as the New BCC coin can apply it self over Bitcoin chain whith another competitor dev team ??

how does BitCoin Core Team approve that    



again in other meaning : can i creat XYZ coin and it  against ETH and promise to give ETH holder the same amount of ETH in XYZ  with out any approval of the ETH dev team ?