I would not use clippings from other properties: insecticides being a primary concern. But, herbicides are an other great concern. Many herbicides are endocrine disruptors, while others persist for a very long time, and can even cause long term poisoning of your garden soil even after they have passed through an animal's gut into their manure, which is then composted and put on the garden. The other concern: clippings heat up super fast. A pile of clippings dumped in my garden will be steamy within several hours of being dumped. So, clippings that are bagged from a friends property may be fine for the compost, or fine if spread very thin in the coop/run. But, my preference is to only use clippings from my yard. You need a bigger lawn!!!
I also never have enough clippings. They go into my coops, and my runs where chickens of all ages go nuts eating them. (and yes, I have chicks also). Never issues with sour crop or crop binding. Well... only one single issue in 5 years time, and I attribute that to the fact that the hen in question had an underlying issue. Clippings also go into gardens, and into compost (standard as well as sheet compost).