Thanks everyone! Her phone number has been blocked. Especially because when we got back after having lunch with our youngest, Caller ID showed two hang-up calls from that number.
She doesn't know which timeshare we own, as it isn't the same one our friends own. The city in Mexico is a large city with many timeshares, so it would be difficult for them to even find us by calling various resorts.
And if through some magic they did show up, the unit we rent for the four of us is a one bedroom, two bathroom unit with a maximum occupation limit of four. We as owners are the ones who list the names of the people staying with us and no one else is even allowed into the resort unless they are on that particular list.
I assume she does this sort of thing because it was worked for them in the past. It just isn't going to work this time. I actually feel for our friends, as they are going to have to deal with constant requests to stay with them in 2016.
Oh, and it appears that they attempted to invite themselves along on our friends trip to Seattle for a christening. I did not know this and my friend says that she was relentless about asking even though this was a family reunion type event with them not knowing a single person there other than our friends.