I have cloned a coin and changed some variable to make it my own coin. I have launched it and have a few mining pools mining my coin. Going through the code I notice I have an error and the reward halving starts over at block 10k. So miners are getting 500 coins per block instead of 250 coins. I believe this sort of change would fork the coin to a new blockchain but I want current holders to keep the same amount of coins on the new fork. How can I change the code and fork the chain to comply with the new info?
Compile the code. Release the new client. Old and new version will disagree at some point in the future (block 10k in your case) et voila, you will have a forked chain.