As you can imagine, quite a bit of blue air was fugging the dining room where I was trying to shorten them. DB got a lot of exercise continually climbing up and down a chair to check and double check. Eventually we both understood what needed doing and I set to, with DB checking me when asked!
After a couple of hours, one of the narrower set of curtains 66" wide, had been trimmed, pinned and also had its liner adjusted. Day two, the next one was at the same stage. After lunch, I sewed them both and they were hung back up. They are not in their final positions (i.e. one bit will sit over and cover up the bracket) as they need to be temporarily held in their creases to get them to hang correctly: