I have a "new" color that has appeared spontaneously in pot with another color.
This is called a sport. A sport is an offshoot of a plant that exhibits characteristics that do not conform to the parent plant. They are typically caused by a mutation. If you propagate the sport through cuttings, the cuttings will also have the same colors as the sport.
I have taken one section pieces from our pots of zygocactus with the intention of propagating the pieces. However when I went on line to check on best potting mix to use, I noticed info saying at least 2 sections, up to five sections should be taken and the first section buried in the potting mix. I don't want to waste the single sections I've already taken as cuttings, and would appreciate any tips on how best to overcome my boo boo, and the best way to try and propagate these sections (have over a hundred of them, and nothing spare on the parent plants to take other cuttings.)
A one-section piece may work too. The best thing to do is try to root the one-section pieces, and with over 100 of them, I'm sure you'll get some (or many) with roots. The most common way to propagate these is to let the cutting dry for 24-48 hours to prevent rot, then place in a moist, but not too wet, propagating mix which can consist of a mix of sand, peat moss, and perlite, or alternatively a well-drained potting soil. Place in indirect sunlight. Here is more on this technique:
Some people say Zygocactus will grow aerial roots if the cuttings are left out to dry in the air for several days. Then they can be placed in well-drained cactus potting soil. You may want to try this with some of your sections.