I like your original idea of weighing down the branches, though rather than attaching weights, I would tie them to long strings (make sure to use a loop, rather than tying the string tight) and attach the strings to rocks or bricks. Four branches would be idea, as you could get a nice symmetrical tree out of it. I've tied down most of my trees (close to horizontal) and in a few situations I didn't leave a central leader. Those trees are now relatively low (7-8') and fairly wide. Of course how big the tree gets will also be dependent on the rootstock.

kristie: Granny Smith on a semi-dwarf rootstock would normally begin to bloom in year 3 to year 5. If you are super-lucky, less, if you are not so lucky, could be more. There is no rule controlling onset of bloom. I had a Granny here that took 7 years to begin blooming, and never did bloom very well before I gave up and took it out. Now I know that summer pruning and shaping might have helped, but I did not know that then. Whether or not a tree blooms is not controlled by the presence or absence of other trees, insect pollinators etc., but by the readiness of the tree itself. Once you begin to see blooms, cross-pollination can become very important. Granny is not an easy apple to pollinate, and there will have to be a pollinating tree within insect striking distance, but it does not have to be in your yard. It could be 100 yards down the street, and it could be a decorative flowering crab or any other type of apple tree. But yes, it does have to be some kind of apple. Be patient with your little apple tree. Fruit trees take time to grow up and produce. Don Yellman, Great Falls, VA

Your trees are in a cycle of biennial bearing caused by not thinning. Next year they'll hardly bloom again because they weren't thinned this year. Prune out the damaged wood this winter. If it only blooms lightly next year you can leave all the apples mostly to try to pull out of the two year cycle. If it sets quit a bit, leave apples spaced about 8 inches apart next year. And most importantly thin heavily and early the next year it has a big bloom, probably 2015. It's too late this year to help anything besides breakage of the tree. Thin off enough to spare the tree any more damage.

Since you like adventure: Yes it is very unlikely the fruit will be worth eating. But there actually was a Granny Smith. From the variety list of Kevin Hauser: "Granny Smith Australia, 1868 Few folk realize that this is the oldest supermarket apple variety. It sprouted from a washtub of French crab apple trimmings tossed out by an actual granny, Maria Anne Smith of the Ryde District of New South Wales." She got it from a seed so there is a chance (probably at least less than 1:200) And since you like adventure and assuming this seedling is growing in your yard's native soil it will make an excellent seedling rootstock if it survives its first year or two (or five). You can practice all manner of grafting onto it with apple varieties who's scions you acquire locally or through exchange groups. Grafting: I bet you can do it! Here is a link that might be useful: Kuffel Creek Apple Varieties List