It's actually a very clever idea. Mothers can keep for years and years, there's no reason why it shouldn't work. There are those examples we see in cheap rag plant catalogs, they've been around for years..
Here's a 5in1 dwarf apple tree!
http://www.eburgess.com/detail.asp?pid=6123
The problem with those is a general lack of vigor when compared with complete plants or even single grafts.
But cherb is a different plant; different environment, life cycle, etc... Things might get easier or funkier as time goes on. There's only one way to find out. But..
The more grafting, the more opportunity for problems.
All that aside, if it works, it would be pretty epic. 5 mothers, 25 cultivars...
I know if I could do it, I would!