I think growing in one pot is a personal preference. I will say, that while it does look nice when the plants were small, as the plants grow larger (think two, three, four years from now) you will have a real time repotting them and separating the plants' roots once they have been growing together for a while. Having said that, I have had cacti that grew fine together for over ten years. They tend to be plants that grow straight up however.
Hope this helps,

Here we go again, it seems like every few weeks somebody wants to grow different species together.

In a nutshell:
It will usually not work long-term, it definitely will not work unless you know your plants extremely well and even then it is not a good idea. Roots become tangled, plants grow at different rates, plants need different amounts of water, food, etc.

To overcome these pitfalls:
Plant each individual in its own plastic pot, then place all the pots together into a larger container and fill in the spaces with gravel so that it looks natural. This way each plant can get individual attention without over or underwatering the others. It is still a tricky thing to do right, all the plants need to tolerate the same light levels and temperatures. If one outgrows the other the whole planting can easily be adjusted.

Thank you for your suggestions. I am going to grow them in separate pots. I read somewhere that when propagating a plant, small pot (2.5 or 3 inches) should be used. The cuttings I have are 10-12 inches long except for Donkey tails (3-5 inches with 2-2.5 inch stems). And I have about 10 vines/strings of each species. Can I put all the cuttings of the same species in a larger pot, say 6-8 inches? Or shold I put 1 or 2 in a small pot unitl they grow?
Thanks!!

Make sure you follow the response given already. My suggestion is not to mix apples with oranges,
they have different growing requirements. Norma