Questions and maybe some answers:
Are your cuttings from the same plant? Hope you're not planning to mix different types (sorry, still don't know the correct terminology.) I just know that you don't want to mix, for example, an E. Bolero with an E. Oriental Dancer.
Are the cuttings rooted yet? Probably doesn't matter.
So if the cuttings are from the same type (genus? species?), yes you can plant them all in one pot. I'd suggest that you start with an 8" hanging basket. Maybe 10". As you probably know, most hanging baskets aren't terribly deep.
If you're on Facebook (or as I call it, the dreaded Facebook) there's an excellent group that has pictures, sales, trades, lots of advice, etc. The name is 'Epiphyllum, trade, sell, buy, open for all'. It is a closed group but an email to one of the admins will get you in. Try Svante Lundquist or Carl Bullock. Everyone is friendly and very helpful. And of course there are a variety of opinions on any question.
If you're not on Facebook, lucky you. But I will be glad to ask your question for you.
BTW, whatcha got?