If one of your sons is a few days away from being fully vaxxed and you are certain they will keep their masks on, then you really need to only worry about the one son who might have received a placebo. The next question I would ask is how long is the meeting? If under 45 minutes, I would send them masked. If more than an hour, I’d ask ask about opening a window or propping a door open and I’d ask my kids to stand near it.
" I object to violence because when it appears to do good, the good is only temporary; the evil it does is permanent." Mahatma Gandhi
"This is the ultimate weakness of violence: It multiplies evil and violence in the universe. It doesn't solve any problems." Martin Luther King, Jr.