Welcome to Bonsai Nut.
Bonsai is a compound Japanese word, with part mean pot or tray, and the ending syllable meaning tree. Literally Bonsai means tree in a pot.
When a tree is growing in the ground, and being shaped while growing in the ground as a permanent part of the landscape the Japanese term, or at least the term used in North America is "Niwaki" There is a great deal of overlap in techniques for bending and layering and shaping between Niwaki and Bonsai, but there are a few differences. There are garden forums dedicated to Japanese gardens and creating Niwaki that might have better information for you than this bonsai forum, but I am not familiar enough to give you a link.
You are welcome to post here. We will certainly try to help. I just mention Niwaki, so that you can get the best help possible.
So post a few photos, tell us how tall you would like the trees to "finish size", and any other plans you have in mind.
It sometimes helps to take paper and pencil, or laptop and paint program, and starting with what you actually have, try to draw out the new design, using the branches that are actually there. Over the winter this can be an ongoing project. Snap an image of the drawings and post them with your photos of the actual trees. Someone on here will probably be happy to edit and or re-edit the images to show what might be practical, with suggestions on how to get there.
One difference between bonsai and niwaki is that in niwaki there is a tendency to use guy wires or guide wires to move or reposition branches. In bonsai we usually would wrap wire around a branch to accomplish the repositioning of the branch. In bonsai pruning can be very detailed and by hand tools. In niwaki the pruning might be done with electric shears. But there is over lap in the techniques and design principals used.