I have been free ranging my babies sense Nov of 2010 and the only way i can keep them out of an area is a hot wire other than that penning them up would be the only way here ,of course i am sure granny don't want a hot wire on her porch
Good luck mabe ya need to do some extra chores for granny to offset the peas trespassing kinda like take grannys mind off the peas and put it on her wonderful helpful grandchild.
I don't know about your peas but mine do not stay anywhere very long before movving on to another place.
I find that mine are very social and want to join in everything that is going on, maybe they just drop by to say Hi. Are they doing damage or leaving their droppings in inapproate places or is their company not appreciated?