Marsha, it's a real downer when the insects munch away on our precious plants. I always try to assess my garden. What things DON'T get eaten? Why? What things get eaten a bit, but make strong recoveries? Are there plants that don't seem to get eaten at all (even if they're considered weeds) and could they be used as companion plants to repel the munchers?
My place has it's own tiny micro-climate and has very different features from properties even 3-4 blocks away. I'm always observing those differences and noting how Nature adapts herself, as well as trying to learn how I can best mimic her.
I've attached a few links about propagating lilacs for you to review:
https://www.flowerpatchfarmhouse.co...xt=To plant your freshly dug,Water it in well.
https://www.ndsu.edu/pubweb/chiwonlee/plsc368/student/papers04/elizabethbruins/syringa.htm
https://sites.psu.edu/lilacpropagation/2014/03/02/lilac-propagation/
I'd also be asking myself these questions:
What do the abandoned homesites have to offer that my garden lacks? Are there companion plants growing there that I could incorporate with my own lilacs? Would it be possible to harvest suckers from any of these sites?
Science has made many strides recently, in how it recognizes the ways plants communicate. If harvesting suckers, try to take several from each location, and with plenty of soil from the surrounding area. This will help inoculate your growing media with familiar organisms and chemicals for your suckers to thrive.
Also, if your pricing rooting hormones, compare them to cinnamon (in all it's forms). Cinnamon is a very good option for encouraging root growth and, if I remember correctly, does have anti-fungal properties! Below, I've included a link to a research article from The National Center for Biotechnology I formation:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405699/
After watching a nature program that mentioned how acacia trees communicate when grazed by giraffes, I found this interesting video on YouTube:
As you can see, I have a very inquisitive and quick mind about the world around us. I just wish my body was as quick!