Well melanie...the graft location does play a part in it. However, most weepers grown by...er...respectable nurseries are grafted at the ground and stake up in attempt to keep the "flow" of the trunk into the canopy. The lower the graft in most cases, the better looking the tree. Of course ideally no graft would be used as they would be propagated by cuttings, but lets not get into that issue. However, some beautiful trees that I have seen were grafted high and the limb structure hid the graft site. In fact, I have a 'garnet' and a small 'tamukeyama' like this.

Jayco, no it does not have to be the leader and by the sounds of it it cannot be at this point. There are definetely ways of coaxing the smaller branches upward without ruining the structure of the tree.

The most beautiful mature specimens of weepers I have seen were not staked with a cental leader anyway, they were "encouraged" to wind and twist their way up to the desired height.

How you would do this? Wiring might be the best option (although care must be taken when trying this with fast growing limbs). Strings and stakes could be used too, but that would ruin the look of the tree for a while.

Having said that, some other beautiful specimens were not staked up very much at all. They were left low and allowed to creep along the ground in a moundy form. It all depends on what you want though.