It all depends on what ride was down to give you the multi experience FP. Assuming your friend received it due to a ride being closed for whatever reason. Weather, ride breakdown, etc
Say you have a FP for The Little Mermaid ride in MK. It goes down and you get a multi experience FP. The email you get will list the rides it's available for and what it's not. So since it's a lower end ride it'll likely exclude say 7dmt, Space, Peter Pan.
Now say you had 7dmt go down..you'll likely be able to use the multi experience FP on any ride in MK.
So it basically goes like tiers. Lower the ride, more headliners will be excluded. Higher the ride, more headliners included.
Then add in if you have a ride go down at night. Say you have Test Track FP for 8pm and it goes down. Your multi experience FP will likely be good for any ride at Epcot that night, and also good at any park the following day (since it went down at night). In this case you'll still get a list that isnt included. When this happened to me with TT, the things excluded were Illuminations, Fantasmic, Rivers of Lights, and Frozen Ever After. Every other Disney ride was available for it.