I'm trying to help my elderly parents plan their EWR 5-hour layover. I gave them both United Club passes, but I keep reading about passes not being accepted due to overcrowding. Does this happen for both C terminal lounges simultaneously, or do they close 1 to pass holders while the other remains open?

They're flying on Sunday, arriving 9am and departing 2pm. It seems like most overcrowding happens during the afternoon. Does anyone have experience with EWR during these hours, and whether I should advise them to visit the C74 or C120 lounge first? I'm afraid the dragons will be mean to them about their passes and they'll be too embarrassed to try the other one.