Mom•Logic's Susan: Anyone who's ever wrangled a toddler knows kids are hard work. How will I know when my elderly parents aren't up to the task?

First of all, let me say I'm old. I'm in my 40's and just had my first child a couple of years ago. My parents are old too, both are in their 70's. They're amazing grandparents, taking my daughter on outings and overnights. Not only is it a huge help, it delights me that my daughter has grandparents who love her as much as I do.

But the past year my Mom's health has started to go down hill. She has problems with arthritis in her spine and tremors in her hand. She's also increasingly forgetful. Unfortunately, none of these ailments are what I look for in a good babysitter.

I know there's going to be time coming very soon when I'm going to have to tell her she can no longer care for my daughter alone. She's a strong-willed independent woman, so I'm quite sure this'll be news she won't want to hear. Especially when I know the private time she spends with her granddaughter is one of the biggest joys of her life.

Other Moms here in the office have already had to make the painful decision to restrict their own elderly parent's time with their kids. Jill, a mother of two teenage daughters, remembers telling her 75-year-old mother her girls could not ride in a car when her Mom was behind the wheel, "She was, of course, infuriated," says Jill.

Diana, mother of a 6-year-old boy came to the conclusion when her mom was playing with her son on the floor and looked at her and said "I don't know how I'm going to get up." That's when I knew," says Diana, "that although she loved her grandson, she would be watching him grow up, rather than fully participating in his physical care."

When do you think it's time to tell an elderly parent you don't feel safe leaving them alone with your child?