My mom has a large family who are now spread out across the country and are not in very close communications. I know most from brief holiday gatherings (when they choose to come every few years.) We are pushing the limit on our guest count, but I still have friends I would like to invite. Of course I want to invite my family members, but I am scared that they will RSVP no and by that time my other friends will not be able to come as well since they didn't get a save the date. Is there a polite way to ask these relatives ahead of time if they know whether or not they will be coming so I can invite others instead that would probably be able to come?