Recast the sentence, or risk losing clarity. Instead of "They took their power(s) of attorney(s) to the hospital," write "They each brought their power of attorney to the hospital" or "They took copies of their power of attorney to the hospital."
Same problem arises with, for example, the title "Book of Mormon" and "Power of Love" You'd have to say "copies of the Book of Mormon" or "versions of Power of Love" to preserve your meaniing.
The correct spelling of the plural of cyclist is cyclists.
correct spelling for duchess made plural is "duchesses."
The correct spelling for the plural noun of "screech" is "screeches".
That is the correct spelling of "dingo" (Australian wild dog).
The spelling of the plural noun, enrollees, is correct.
That is the correct spelling of the word "sky" (plural skies).
That is the correct spelling of the plural of philosophy, which is "philosophies."
The correct spelling is deaconesses.
That is the correct spelling of "trainer" (an athletic coach, or animal tamer).
The correct plural spelling of the first name Frances is Franceses.
That is the correct spelling of "firefighter" (fireman).
The correct spelling isdilemma.