When I "do" beet pulp, by the way, I soak it at the rate of one part beet pulp to two parts water. If you're using cold water, it takes about three hours minimum for the pulp to soak up the water (it takes about half an hour if you use really hot water but I found my horses seem to prefer it cooler than warmer). I don't know how long you're soaking your cubes but you'd want them done at the same time, I'm sure. Since you'll have them done at the same time, I see no reason why you can't just dump them all together in the feed bin. When I used to feed my senior horse, I'd dump the beet pulp in first and put his soaked complete feed in on top of it - he was fine with chowing down that way.