The sister is the older of the two kids. If her brother is 14, she must be at least 18. And, now that you mention it, even when the two boys were getting together in grade school, she or the mom often made the initiating phone call. I thought it was weird then. So, as adorable as my son is, I don’t think she has the hots for him.
The family dynamic there has always been odd. The brother is the only male in the household. His mom looked perpetually downtrodden. I suspect he bullies his mom and sister, too. Maybe he considers the two of them to be his social secretaries.
I think my son and the other kid just run in different circles, although I don’t know whether or not the other kid is in with a bad crowd.
Two more calls today, by the way, both from the mom suggesting the kid come to our house.
Anyway, combining advice from various Dopers, I think the next time the mom or sister calls, I’ll answer and tell her, “I’ve let my son know that you’ve called. He’ll get in contact with John if he wants to get together with him.” If they keep calling after the “Don’t call us, we’ll call you” message, I may have to be more direct.
I really appreciate everyone’s responses. It’s helpful to know I’m not the only one who finds the whole situation a little creepy.