Lifetime transfers: gifts in consideration of marriage or registration of civil partnership: IHTA restriction of Rennell - the eventual recipient
A further restriction under IHTA84/S22(3) and (4) means you must be careful to identify the true donees of gifted property. If the donee takes the property under a legal obligation to transfer it to another person who is not a party to the marriage or civil partnership the exemption is not due.
However, if the donee is not under a legal obligation but subsequently transfers it voluntarily, you can disregard that transfer. This applies even if the gift was made in the hope that the donee would make the subsequent transfer. Re Park (No 2)  2 WLR 276  1 AER 394