Philadelphus?

Looks like deutzia gracilis

Deutzia.

Thanks so much!!! Deutzia gracilis it is!

Now to try and start one from the heavy pruning I have to do to keep their plant over on their property ;)

You shouldn't have to try to start one. They are very generous with babies of their own, usually tucked in under the foliage near their base. If you follow the stems down to the ground, you'll see they're not part of the parent plant's crown. We pull half a dozen off of one plant site each spring. This year we used the volunteers to start a hedge of them down a terrace bed. They're not at all invasive......it just looks like the crown is thickening, but they'll start a stand of them if you leave them undisturbed. I love them. Nice shrub and underused.

Thanks =) Unfortunately I can't trace branches down to the base of the plant because the base of the plant is on my neighbor's property on the other side of a fence ;) I'm hoping to start one from cuttings....

If you're cutting them off on our side of the fence, that means you have some branches on your side. So, just tuck a branch down to the soil and peg it down and layer some starts. They layer easily. That's how the babies often start that we dig up and move. They just start to root up where a branch touches the ground.

Hmmm.... I wish they would start that easily by being cut and stuck in soil! All I have on my side of their fence is concrete =\ My garden is further down... hehehe...