@Tom826 Whether you will be required to pay extra or not or even if your kids will be allowed to enter the unit is entirely dependent on the individual host, the condo rules, and how it plays out when you discuss this with the host. A guests who asks, rather than assumes, would never be considered a bad guest, only those who just assume it's okay to have visitors or balk at an extra charge for this, rather than just saying, "Okay, thanks, will have to look for a listing that's a better fit for my needs."
And if you have good reviews, a host would be more likely to accept this.
An extra charge may seem unfair to a guest, but they often don't realize that the price for 1 guest is based on average utility and amenity usage for 1. Just because visitors aren't spending the night doesn't mean they won't be showering in the condo after using the pool or gym, using up hot water, dirtying towels, using toilet paper and soap, helping themselves to coffee, deciding the AC needs to be turned up to Arctic temps, etc.
You sound like a responsible person. Just communicate honestly what you need in terms of your kids visiting, which means communicating with the host first via an Inquiry message, rather than a Booking Request or Instant Book.