English to Spanish Bus/Financial Law: Contract(s) National Heritage

Hello all... I know this word has been asked before, but I am not sure how to apply the correct translation within this context. It is an extract from the National Heritage Act of 1983 from the UK. The sections talk about the "initial vesting", "gifts vesting on or after vesting day".

I am guessing it is about the Acquisition of rights for the collection they have at the museum so the correct translation should be "adquisición de derecho"?? So would it be correct to say "Adquisición de derechos iniciales " and "obsequios en el día o después del día de la adquisición de derechos". For some reason it just doesn´t sound right to me.

Many thanks for your help!