We have recently regained custody and care of 80+ year old lilacs that have great sentimental value to our family. They have been neglected for decades so looking for guidance on how far back we can prune them to help and not harm. (Height and overall size are not an issue, there is plenty of room for them to grow). Obviously the dead trunks/branches can be removed but how many of the larger suckers growing around or on live trunks/branches are safe to cut away? I will attach 3 photos that show what is left after we have pulled weeds and cut away the smaller tender suckers around the perimeter. Thank you in advance for your time!