How will grafted prairie cherry plants - Romance Series - grow? Possible to get them growing on own roots?

I just bought 4 grafted prairie cherry plants. Juliet and Cupid on rootstock Prunus avium, Valentine and Carmine jewel on rootstock Prunus mahaleb. Also got Evans on its own roots. Will be growing in Dublin Ireland - cool maritime zone 8b - in a sheltered SE facing site on good soil. What size will these grow to? I would prefer a suckering multi stem bush, rather than single stem trees for easier management. Is it possible (or preferable) to get them growing on their own roots by layering?

I can only speak from hands on experience about carmine jewell and let me just say these suckers sucker!
It’s not necessarily a bad thing to get suckers but if you have them on their own roots expect a plethora of plants coming up! I’ve heard multiple times Juliet is the same way Juliet Cherry . In regards to height 12’ height is not unusual for carmine jewell Carmine Jewell Cherry Yields increasing with age. In terms of propagation I can’t say from a legal aspect if you can or can’t but can say some have found them easy to propagate Hope that helps.