We are glad you are reaching out for help and suggestions with this issue. It is not only frustrating but dangerous. It will take some practice, but with patience hopefully you will be able to modify this behavior.
We suggest you practice at home every day several times before going back to the park. At first, in the house by pretending you are at a park or somewhere and you are holding his hand. Then talk to him about staying close where he can touch your leg. So let go of his hand, but he must touch your leg with his finger. Walk around that way for a while and praise him if he keeps touching you with his finger. When he consistently will comply with that, allow him to walk far enough away from you that he can no longer touch you, but your arm and hand can touch him. Practice that for a while and if he will stay within that range, praise him for doing it right.
Then, and only then, do you have him practice going out from you where you cannot reach him and then ask him to come back and take your hand. If he will do it, make a BIG DEAL of it. Use wow words and a pleased voice tone. In other words, celebrate his success! When he can consistently come back and take your hand, then allow him to go farther away and you may even go for a walk outside to see if he can remember to do this when in a different setting or environment. Use preventive prompts reminding him that as soon as Grandma says “come back" that he stops what he is doing and hurries back to take your hand.
If he doesn't come back, then he has not learned a “new way" to respond, so back into the house you go. Do not take him to the park until he can come back when you ask him to. When the time comes that you can go to the park, practice his finger on your leg, then your arm and hand touching him, then a few steps away and coming back when you ask. Then allow him to play away from you and test him to see if he remembers. If he does not, then playing in the park time is over until more practice occurs.
Remember, you are shaping and molding a new behavior to replace his dangerous one of running away from you and from his parents. Keep them involved in your teaching and practicing so they know what he is supposed to do and be consistent with your expectations and use of consequences. Use lots of praise and reinforcement when he does what you ask. When he doesn't, it is back to square one.
There is a great book available called Common Sense Parenting of Toddlers and Preschoolers. It is a Boys Town publication and teaches simple responses to children's behaviors, both good ones and not so good ones. It would be a good investment for any parent or grandparent at $15.95. Check it out online at BoysTownPress.org or by calling 1-800-282-6657. It can be helpful with your current situation and many others that will occur in the upcoming years.
