Often people getting divorced can (or want to) individually, or in agreement with their spouse, take money out of the marital estate to benefit their children or grandchildren. Right now individuals are entitled to gift $13,000 a year per person under the government's annual gift tax exclusion.
A special "gift-tax free provision" allows you individually to contribute up to $65,000 in one year (or you or your spouse to contribute $130,000) per beneficiary as long as there are no further gifts within a five-year period.
The additional benefit is that that contribution to a Section 529 plan is normally removed from your estate for estate tax purposes.
Always check these and any other approaches with your lawyer and accountant.