My friend has a Christmas cactus that belonged to her grandfather and has grown too large for the pot, which is rather heavy. We are wondering if the plant can be broken into smaller plants without killing it.
Repotting Very Old Christmas Cactus
I have several thoughts. 1. Christmas cactus is easy to grow from stem cuttings, even a single leaf; 2. You are likely to find very little soil and just a jumble of roots when you unpot it. Untangle the roots by briefly soaking the rootball. If you find roots supporting a stem, use pruning shears to make a clean cut then repot; 3. Christmas cactus can be pruned back to a more manageable size. Use pruning remains to start new plants. The less you handle/remove roots the better as the tiny feeder roots are easily damaged. https://www.wikihow.com/Care-for-a-Christmas-Cactus