My mom has epilepsy and she is usually fine with just closing and covering her eyes when there are strobe lights, don't know if this is the case with your party.
Here's the post regarding the issue from the disABILITIES faq
There are not actually any attractions at WDW that use lights that are technically strobe lights (i.e, fast, regular flashes of light) and they do not have any warnings for seizures and/or strobe lights on any attractions. Where they do have flashing lights, they are always irregularly flashing, which is a different situation.
Most true strobe lights flash many times per second, but slowing to 5 flashes per second or less means that the majority of even photosensitive epileptics are not going to have a problem. Only about 3-7% of people with epilepsy are photosensitive and have problems with lights; of those, only about 5% would have a problem with a light flashing 5 times per second or less.
If you do encounter flashing lights and are concerned, the Epilepsy Foundation recommends covering one eye and turning/looking away from the direct source of light. The reason for covering only one eye and looking away from the direct light is to prevent both eyes from sending exactly the same information to the brain.
This should work whether someone has a problem with epilepsy or has problems with lights for another reason.
This is a list of attractions I know of with light effects of some type. Many attractions have a single light or 2, so it is difficult to list all. But, I am sure that we have included most of them.
MK
Enchanted Tiki Room - periods of darkness with simulated lightning. The lightning is random and short.
Pirates - some lightning flashes in the first dark part of the ride.
Big Thunder Mountain Rail Road - there are no light effects in this attraction, but if you are riding on a sunny day, you will go in and out of dark tunnels repeatedly at high speed.
Splash Mountain - on a sunny day, there are several places where you will go from dimly lit indoor areas to outdoor. The ride moves slowly, so the change is slow. There is a single bright flash when your picture is taken during the big drop.
Haunted Mansion - almost at the end of the preshow, there is a flash of lightning at the top of the ceiling.
Buzz Lightyear - just before the last room of the ride, there is a long narrow tunnel room with swirling red lights and flashing white lights. The swirling and flashing are not rhythmic.
Stitch's Great Escape - Most of this attraction takes place in the dark, but there are some random light flashes at times (while looking for Stitch)
Space Mountain - flashing lights
Epcot
Spaceship Earth - the first part of the ride and the last part of the ride are dark, long and narrow.
The entrance 'tunnel' has screens high on the wall, warning that your 'time capsule' will turn and descend at some point during the ride. The screens are bright compared to the walls.
The exit tunnel has some lighting effects, but not flashes.
Ellen's Energy adventure - includes a movie where parts are dark and then light suddenly appears (the 'Big Bang' theory of earth's creation)
Mission Space - Includes a flash of light for a picture.
Test Track - includes a light flash for a picture. Also, during evasive maneuvers test, your ride car will be in a dark area with bright truck lights suddenly appearing in front of you.
Living with the Land - simulated thunderstorm. The first part of the attraction is dim; the second part is in a greenhouse, where the light can be a bit of a shock when you first enter. The ride boat moves slowly though.
Soarin' - the end scene includes fireworks
Journey into Your Imagination - Some flashes of light. One bright flash near the end where a picture used to be taken.
El Rio del Tiempo (Mexico) - fiber optic fireworks in the ceiling and wall in the last scene
Maelstrom (Norway) - near the beginning there is a spinning, pulsating light. It is irregularly pulsating
American Adventure - the Chief Joseph sequence has a few stokes of lightning
Studio
Star Tours - flashes of light during the attraction (you are in a space ship and end up in a spaceship fight)
Voyage of the Little Mermaid - some flashing light, some twinkling lights and some pulsating blue lights above your head to simulate the top of the water. All are random
Rock N Roller Coaster - one bright flash of light during picture taking
Tower of Terror - one bright flash of light during picture taking. Elevator door opens suddenly to give a view of outdoors (so bright light on a sunny day). Some twinkling lights during the early part of the ride and I was too busy being scared and holding DD down to notice any more.
AK
Festival of the Lion King - one act includes twirling flaming sticks
Dinosaur - dark ride with sudden appearance of dinosaurs in front of you. Random flashes of light. One big flash as a picture is taken.
Expedition Everest - includes some bright light effects
My mother has migraines and finds that reflections off water (especially the World Showcase Lagoon) bother her on a very bright day. She also has problems sometimes with the 360 movies in China and Canada because they are all around.
This is why I love Disboards and Disney people! I've been over 20 times and know most things Disney, but had no idea about this. 
