How to plan full-time and part-time working schemes?

Hi! Up to now I’ve been allocating the correct amount of working hours per week for each of our team member in Portfolio Workload. Problem: for people working part-time this is not precise. Eg a person working 24 hours a week on Mon, Tue and Wed, should be available in Asana on those days and not on Thurs or Fri. But setting 24 hours in Portfolio Workload Capacity spreads the 24 hours over 5 days.
Are there better ways to organise this? Thanks!

Workload currently does not allow this. The only workaround we found was to consider the full-time but assign them on full-day tasks for when they are not here, so that the workload looks like they are busy.