Got it- my post got merged into this thread, but this thread is helpful.

From what I've gathered

1.) You can bring as many as guests as the lounge allows (i.e. not make it too full for their business class customers).
2.) Citi has a very narrow definition of "immediate family"- it's a spouse and children under 18
3.) Citi has the right to verify your extra guests were immediate family, but it is very unlikely they will charge or investigate you as long as you don't have a pattern going over the limit. (I actually couldn't find a single post online about someone ever being charged)

So while my spouse, sibling, and two parents are technically 1 over Citi's limit as defined by their policy, it is very unlikely I will be billed.