i've read this 3 times and still feel like i'm missing something here... if you asked for address in may for june birthday your request wasn't a month late it was difficult child's response that was.
I would tell difficult child that it is important to you that your grandchild understands you didn't "blow off" their birthday, their father just has poor etiquette or can't return a message.
sending hugs and good energy your way
nancy
