@Rasheda3 I see two possibilities of what's going on here:
a) First-time guest mistakenly forgot to input her guest count when booking, but legitimately intends to bring only a group of 4. If this sounds convincing to you, you may submit a change request, but insist that the group may only check in after confirming the request and additional charges (if any) and submitting the names of the other guests.
or
b) This is a Trojan Horse Guest that actually intends to take advantage of your relative newness as a host and bring a much larger group to the home for a messy, destructive post-game party. This happens so often, you really can't let your guard down - even if you allow the increased group size, you'll need to make it absolutely clear that nobody who isn't named, registered, and paid for in the booking will be permitted on the property at any time, and keep the home monitored (whether by external cameras or your own eyes) to back it up. One night's booking fee can't possibly compensate for what an out-of-control group is capable of doing to your lovely house.
Either way, don't feel obliged to allow the early check-in. Being politely firm about your boundaries early on helps set the tone that you might need to maintain in case there's any funny business. And for future requests, it's always suspicious when someone tries to book a whole 2-bedroom house solo, so make sure to check whether this was a mistake before accepting.
