Investors and rental owners

Already had answered "yes" to the two top questions in column 3 but this still doesn't allow to split the capital gains - only by overriding line 12700 in both returns. 

 

Others have suggested that schedule 3 could indicate a splitting of "shares" between spouses so that each claims 50% of the gains but I can't seem any way to induce that in the CRA form Schedule 3.