Others have replied with good ideas. If these don't work or if you can't move her (understand it is your neighbors hen), try going to the main search area at the top of the page and typing in "broody hen break". There are a lot of results and replies that might also be helpful. Sorry that is all I can offer as I have not had this issue. Good luck!
Hoping that the rain holds off... today is our first official day of furlough. DH is off fishing and after a weather check I decided to get up and wait for daylight so I can get straight to work on the coop. Trying to finish up before the rains come again! It poured here yesterday and what seemed like all night. I had stopped emptying my rain gauge and just let it fill up. Noticed a couple days ago it was around the 3" mark, this morning - overflowing. More than another 2" of rain in the past couple of days. Need to mow the yard again at some point...