I have a 529 Plan strategy question.

Suppose that the future student and his parents live in NY State. The grandparents live in Connecticut. They want to open a 529 Plan for the future student. The grandparents want to get the state income tax deduction for the contribution, since they are making the gift. Does that require that they open a Connecticut 529 Plan? Does it also require that one of the grandparents be the owner of the 529 plan? If the grandparent (donor) must be the owner in order to get the State of Connecticut income tax deduction, does this mean that the value of the 529 Plan will be included in the grandparents’ taxable estate when they pass away?

There are also great grandparents who are NY State residents. If they want to make a contribution to a 529 plan, would they have to open a separate 529 Plan in NY State with themselves as owners in order to get a State income tax deduction?

Thank you