For small edits (like those of players I "Traded") the save states will still work, it'll just mark the stats on the original player, unless you change that player's name in the .txt file that corresponds with that team.
I'm playing an 80-game regular season (with MS Excel tracking standings, and the Stat-Keeper just keeping my Quebec team stats). Midway through, I "traded" Owen Nolan to New Jersey for Valeri Zelepukin (Just by putting those players stats in the other player's slot with the NHL94 editor). I put Zelepukin's ratings and name over Tony Twist (please forgive me, Twister!) and moved Tony Twist's ratings to Owen Nolan's, keeping Nolan's name in place. Then, I went to the .txt roster file in the Quebec folder and changed "Tony Twist" to "Valeri Zelepukin", also changing the number and overall rating to match Zele.
When I import stats into the StatKeeper, it shows Owen Nolan's stats through the first half of the season, and show's Zelepukin's since the trade. Without altering the roster, it would just say those numbers by Tony Twist's name.
Hope that long-winded explanation helps! Love all the work and ideas you people are sharing! Great Web site!