Slumber Party RSVP Website: Beds, Pickup Times, and a Named Adult
A slumber party RSVP has to count beds and overnight yeses, because a living room that fits a movie does not fit six air mattresses and a parent expecting pickup at ten.

A slumber party breaks when the invitation says "sleepover" and half the replies mean "we will see." You are not hosting a movie. You are responsible for other people's children in your house after their parents have gone home. That means a real bed or a real spot on the floor for each child who is staying, a clock time for each child who is not, and a phone number that works at midnight.
You can create a slumber party RSVP that forces a choice: staying overnight, pickup at a time you name, or no. "We'll play it by ear" is how you end up short one pillow and one parent who is already asleep.
Count sleeping spots before you count friends
Walk the room you will actually use. A queen air mattress sleeps two only if both children fit and you are willing to put them there. A couch sleeps one. A floor spot needs a sleeping bag you own or one you have asked that family to bring. Write the number down. That number is the overnight cap. The number of kids in the class group chat is not.
If you only have four spots, invite four overnight guests. You can invite additional kids for the evening and send them home, but only if the form separates those two groups. Mixing them on one yes/no question is how a parent hears "sleepover" and plans to drop a backpack.
Say where the children will sleep, in plain language. "Girls on the air mattresses in the den, bags by the door" is a plan. "We'll figure out the sleeping situation" is how someone ends up in your bedroom or in a room you meant to keep shut. If a sibling is not invited, say that in the first paragraph. A plus-one little brother does not fit a party you sized to the floor.
Overnight, late pickup, or not coming
Give every child one of three answers, and do not accept a fourth:
Staying overnight — counts against the bed cap, brings the bag you listed, and is picked up at the morning time you publish
Evening only — picked up at the clock time you set, with the name of the adult who is doing the pickup
No — so you can offer the spot to the next family instead of holding a mattress for a maybe
Put the evening-only pickup time on the page, not in a text you send later. Parents plan the rest of their night around it. If that pickup is 9:30, a child still in your kitchen at 10:15 is a different event than the one you hosted. Ask for the pickup person's name and number on the same reply. "Mom will get her" is not a name.
Morning pickup needs the same treatment. A breakfast you are cooking for six is not a breakfast for six plus three parents who arrive at 8 and stay through coffee unless you invited them to. Say whether parents come to the door or come inside.
Meds, food, and the call you may have to make
Ask what each overnight child needs before bed: an inhaler, a prescribed dose, a night light, a pull-up, nothing. You are not a clinic, and you should not discover a medication in a backpack with no instructions. If you will not give medication, say that, and the parent either skips the overnight or stays. That is a fair rule.
Food is the other midnight problem. Ask for dietary notes that name the food, not "she's picky." A nut allergy and a child who will not eat pizza are different shopping lists. Snacks you planned to leave on the counter are a bad plan if one guest cannot be in the room with them. Say what you are serving and what you need them to bring if their child will not eat it.
Every overnight yes needs an emergency contact who will answer. Collect a second number if the first parent is the one who might sleep through a call. If a child cannot stay without that number, the form is not done.
Photos, lights-out, and the house rules
Sleepover photos travel farther than birthday photos because they are taken in a bedroom or a bathroom with kids in pajamas. Ask for photo consent before anyone arrives, and say whether you will post anything at all. If the answer is no posting, tell the kids the same rule. A parent who said yes to attending did not say yes to a story post.
Write the house rules on the RSVP in a few lines: no leaving the house, no kitchen knives, phones charged in the kitchen after a time you name, and what happens if a child wants to go home. You want the parent to have read that before drop-off, so the 11 p.m. call is a plan and not an argument.
Close the list two days before you buy breakfast and lay out the beds. A Friday-night add means you are short a spot you already counted. Export names, overnight or pickup, pickup adult, food notes, meds, and the emergency number. If overnight yeses are over the spots on the floor, call someone before they pack a bag.
A slumber party RSVP is finished when every child has a spot or a pickup time, every overnight child has a reachable adult, and you know what you will and will not give them at bedtime. The movie can be chosen last.