Thanks Ropster, i guees you could bulk up with the cookers and use eaters to add the sweetness. Any ideas on ratios
I've got 2 cooker trees and 5 eaters + use eaters from my in-laws tree, which is perfect for the 1:3 mix (cookers/eaters - and I try to use 2 different eaters) I use for pasteurised juice, cider and apple wine. I also collect quite a few windfalls from a couple of 'orchards' in local gardens, and press well over 100 gallons of juice p.a. (Just planted another 7 trees!)
The eaters do not "add the sweetness", but the cookers add the required acidity.
Those cookers actually contain around as much sugar as eaters, and crab apples very often contain more sugar than eating apples - but much more acid, so I sometimes use them to mix with eater juice to 'crisp' it up a bit (max 10%), but pressed crab apple juice can mature to give a stronger flavour (& colour), so I limit it to 5% in wine/cider.
As pressed juice from some varieties will taste much better than eating the apple itself, I would suggest pressing each variety separately, then blending. I've always found that a pleasant, crisp tasting juice will be suitable for fermentation.
If the apples you wish to blend come at different times, you can freeze the juice for later use, but what I do is pasteurise both drinking juice and single varietal juices for later use using a Vigo electric pasteuriser. This is also useful for blending juices from biennial cropping trees out of sync. and for saving cooker juice to use the following year with early eating apple juice - from trees that crop before cookers.
A useful site for cider & juice (for apple wine just add more sugar!):
http://www.cider.org.uk/