Last point from our resident SPHR:
""If you are talking just PTO or Sick time, yes that is legal to share with other employees as long as the specifications are laid out in a company procedure/policy. In my last company, we shared PTO and Sick time by the hour so we would just transfer out of one accrual balance to another. Of course we had a form, approval process, etc. for that. That would be the only benefit that it would be legal to share, but sharing of time off is common!