It's my ds birthday party and we have hired a soft play for a private party. Now ds has invited his school friends etc but a lot of them have younger siblings. Do I inform them that if they want to bring them the softplay will charge a entrance fee and party food is not included or is this common knowledge. Apologies but I only have one ds and didn't want to upset anyone on the day. Should I pre warn them as we have paid the set fee for the children who have been invited.