Very nice! I knew I had it but didn't feel like trying to figure out which combo of squares was "correct" so just revealed
It might take a little time but what you could do (if you wanted) is add each alt as an individual square. So if the base grid had all "T"s you would add 4 total alts - each one with one T changed to an F. That way any combo of Ts and Fs would be accepted. If you wanted to accept TF as well you'd need 8 total alts.