What are the vines?

confederate Jasmine and chocolate vine

So, not too enormous. I've seen Akebia quinata growing through a small tree. I don't think you've anything to lose by trying the idea but there might be problems with lack of light to the vines.

You need to add something else. I think that will look weedy and eventually become a hazard, or at least an eyesore.

I think that would be fine so long as they get enough light. The jasmine that I have grows like a weed, so you may want to trim it back every now and then, but I don't think that those vines would kill a tree the way that non-native wisteria and English ivy kills trees. Cross vine is another vine that can grow on trees without killing them.

The OP has Confederate Jasmine i.e. Trachelospermum jasminoides, not a true Jasmine. I have one and it is not going to swamp a tree. The other vine, Akebia quinata, I see every day on my walk to walk growing through the lower branches of a tree. Neither will hurt a mature tree imo. The only question is whether they can be persuaded to grow where the OP wants them to go and whether they will get sufficient light.

It's size of tree vs. size of vine. These need to be well matched or host trees can be overwhelmed. Five Leaf Akebia can get pretty big, I've seen one that had grown to occupy several hundred square feet of a vacant lot on Bainbridge Island, WA (USDA 8). A better-written-than-usual, illustrated garden plant encyclopedia I have sitting here gives a height of "30 ft (10 m)" for this one.

My jasmine has grown from 4 to 15 feet in two years, getting only 3 hours of sunlight per day. YMMV

Thanks for the comments all. I'm attaching a pic so that it might be easier to visualize. I certainly don't want it too look "weedy". I had some flagstone steps installed recently and the landscaper designer talked me into using creeping Jenny between them (for soil erosion/decoration/etc). Ugh, I hate it. It looks leggy and weedy. I'm going to replace it all with Irish moss.

Anyways, if you look at the pic you can see the low branches that I thought I could pull down and thread some vines of the jasmine and chocolate vine through. i just transplanted the jasmine which is why it looks sad and brown right now. I also bought a Boston ivy that is leaning up against the side fence right now. Thinking about using that too but where to plant? Not sure.

Now I see the situation I really don't think this is going to work. The tree branches are too far away from the vines. If you pull them down they'll just spring back up and rip the vines. They won't stay down. I'd suggest adding trellis to the top of the fence if you want to increase the height. Boston Ivy grows huge and would swamp the Akebia and the Trachelospermum imo.

btw I am surprised that your Creeping Jenny is 'leggy'. I've never seen it anything other than flat to the ground. Is the plant id certain?

Thanks.....I was afraid of that too. I can buy some cheap 2feet trellis at Lowe's and nail them to the back of the fence and give them a little more height. Maybe that would make it high enough to "connect". If not, at least I'd have more height. Maybe scraggly is a better word than leggy....see pic. I just don't think it looks very neat.

Lisa, I think the trellis is a good idea, and would really add to the aesthetics of the fence. If it is relevant to you, I saw some almost-two-feet trellises at Dollar Tree yesterday.