There is absolutely no point in enrolling an 18 year old in a 529 College Savings plan. Those plans are designed to grow money tax-free OVER THE LONG RUN for college expenses. If the family needs money to pay for college, you can simply gift money directly to the school, without tax consequences, to help pay for tuition.
If you have younger grandchildren, by all means open an account — or several accounts in Bright Start. You’ll get a tax deduction up to $10,000 on your return for your contribution to the plan. And although you can change the beneficiary on the account, it might be more equitable, and equally easy, to open a plan for each grandchild separately.