My last place had beautiful very old lilacs everywhere and when I moved I dug down and took root cuttings, left them in a five gallon bucket full of water for a few weeks until I got to them and planted them.Gayle in KY said:Aren't there any little plants growing near the base of your lilacs? If so, you can dig those up and put them anywhere you want.
There was a big, old lilac bush in the yard when I moved here. I've moved several small plants to other places in my yard (I love them, too!).