Originally Posted by 24left

Based on my recent experience guesting in someone to a PPL (Plaza lounge), I hold the membership and it entitles me to a guest. Do your nephew or either of your parents have PP membership (either owned or via AMEX Plat)?

Without it, I imagine the only way to get it is with a lounge invitation (like the one CX issues for the PPL at YYZ etc), or to pay.

Am I correct in understanding your post, that the seats you redeemed for your parents is in Biz Class?

If yes, then I would assume that seat/ticket would include access to a lounge.
CX experts here can confirm.
No idea what the lounge access rules on a reward ticket state or whether those rules include the caregiver.