I am going to reiterate what I said earlier.
Please contact a financial advisor ASAP in regards to saving for college for your Grandchildren. A 529 is not always the best way to do so. here is why:
Funds in a 529 account can be used for approved educational expenses only. If your GC does not pursue higher education, or does not need the money for his higher education, that money can be pulled out by the account owner, your AC. He will pay high taxes and penalties for it, but it will be his money at the end of the day. If he has multiple children with 529 accounts, he could transfer any funds in your GC 529 to another of his other children's account.
Depending on your state, your AC and not you, may be getting the state tax benefit for your contributions.
I say this from experience, as I have both a 529 (which I am trying to empty to be rid of it) and a ROTH IRA for college money. The benefits of a 529 do not outweigh the benefits of a ROTH IRA or other savings in terms of effectiveness or tax breaks.
In a case such as this, it may be more beneficial to you to put that same amount of money into a regular savings account for your GC when he turns 18 or 21. Or a trust. You can make stipulations that it will be used for higher education purposes.
As for the estrangement, I am not going to advise. But knowing just what I know from the OP's posts, I would:
Continue to support all my GC equally in terms of money for the future.
Contact a financial advisor immediately and discuss what options are best in this scenario. That may or may not be a 529 account.
I can say that my financial advisor does not recommend a 529 at any point, because of the limits stated above.