CGT on selling a shared ownership residential property

We a selling a second home 50% owned by my son and 25% owned by my wife and myself. Before submitting our individual tax returns can we: 1. Put the Allowance, Legal and Estate Agent fees and improvements totals against my sons 50%of the property rather than trying to split the share across the three of us? 2. My son and I are both higher tax payers, however our individual gains will each be below £50k. Does this mean we can claim the lower CGT tax rate of 18%

Hi Roehampton wood,
No, all income/expenses must be split according to ownership.
Thank you.