Are French Lilacs Grafted?

Are lilacs, such as the big beautiful French lilacs grafted? I ask because mine died. It left suckers some 3, 4, or 5 years ago. Will these suckers come back true to form or were they below a graft and I am waiting for something that will never come?

The lack of bloom could be due to not enough light or too much water. I would move one or two and try to improve both drainage and sun location, but if it is a rat, I am better off buying a new plant. I so want a thriving lilac. My little Kim does just fine, but is not the real deal in my thinking. Can you help?
Thank you. Smiles.

By NWRose