I apologize for this delayed reply to your gardening question and hope it is still helpful to you. Your options on the lilac are to either dig the plants and transplant is which is possible if you keep the roots moist and keep the plant out of direct sun until you get it planted, or to take cuttings which also is possible but just means you have to start over with a very small start.
I'd do both with the cuttings being insurance. Get as much of the roots as is practical and cut the top back by at least half or more to make it more manageable. Reset the plant as soon as you can and keep the soil moist but not soggy on through the summer.
Thanks for the question. Best wishes for a wonderful gardening year in 2007. Please stop in again soon!
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