I might just make it simple and sell the SPY and buy like 75 extra shares of QLD. It probably isn't equivalent but it doesn't really matter, I just want to focus on QLD right now.
Then again, that will change my starting amount and make all subsequent adds larger.
I might just close the SPY position and continue on with the QLD as is, because a few points up with QLD will cancel out the loss from selling SPY early, anyway.
One thing that will be different is QLD doesn't pay a dividend, so holding positions for extended periods of time won't pay any extra.