If we gift money to our children but ONE of us dies before 7 years?

macman

Your children won't pay any IHT. IHT is due from the estate of the deceased, and must be paid before any distribution of assets is paid.
In the meantime, you can make regular gifts to them from surplus income, if you have it.
But, given the apparent size of your eventual estate, why are you not taking professional advice on sensible tax planning to mitigate the amount of IHT that may be due?