IHT and lifetime gifts from married couples

I am familiar with the concept of Potentially Exempt Transfers (PETs) which become fully exempt from IHT provided the donor survives for 7 years.
But what happens if the 'donor' is a married couple - with no defined apportionment of the gift between partners - and one survives for 7 years and the other one doesn't?
Is 50% deemed to have come from the deceased partner, and thus liable for IHT, or maybe causes a reduction in the amount of unused allowance that can be transferred to the other partner, or what?
Reply to
Roger Mills

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