What size are these trees now? Any branches?

First, try to find out what rootstock you have for dwarf and semi-dwarf, this will help determine the size of the trees in question. Also the varieties will determine size.

Now, how tall you want your mature trees to be?

Once you have this information - imagine the shape you want the tree to be when it grows up.

Keep me posted and we can discuss what needs to be done.

Ted