If you have PTO, you have to be allowed to use it, BUT the employer does have discretion to tell you to use it some other time, if the time you propose to use it is bad for them (e.g. they are understaffed then; it is a critical or busy time; other employees had previously scheduled time off then; etc.). The law allows the employer some say over when PTO is used, so long as they allow the employee some reasonable opportunity to use it; that is, while they can't deny you use of your PTO, they don't necessarily have to let you use when you want to.If your employer is large enough to be covered by the Family and Medical Leave Act (FMLA)--at least 50 employees located within a 75-mile radius--and you are eligible--worked there at least a year; worked at least 1,250 hours in the past 12 months--you may be able to take unpaid FMLA leave (for up to 12 weeks total time; it does not need to be taken all at once, but may be "intermittant") to care for your father; while it is unpaid,  they cannot legally interfere with it if they are covered and you are eligible. You can find more information on FMLA leave on the U.S. Dept. of Labor website.