Hello, I have (had) 3 lilacs at the house I moved in 3 years ago, and they've looked increasingly rough. They're in full sun but do have some encroachment from the neighbors' overly aggressive English Ivy (ugh!). Only 2 of them came back this year, and half of the shrubs didn't get leaves at all. At least one of them has a decent chunk of it that is still green, but the back half of it is completely without leaves and dead. See photos. Any idea what's wrong with them and if there's a way I can salvage them for next year? I'd love to move them to a different location.