Line Etiquette at Disney
On the face of it, this would seem to me to be a complete non issue. If you want to participate in an attraction - whether it be to ride a ride, or to see a show - the process should be a "no brainer". You step up to the end of the line, you wait your turn, you ride the ride.
First and foremost, you should know that Disney's official policy is that line cutting in any shape or form is not permitted. Cast members have the right to ask you to leave a given attraction for line cutting, and if you are a repeat offender or are belligerent and rude, they may have you removed from the park without refund. In practice, Disney tries very hard to make all guests happy, and they seldom enforce the letter of the law unless a situation shows it to be absolutely necessary.
To avoid any issues, please observe the following guidelines when dealing with attraction lines at Disney.
Gather your entire party before joining an attraction's line queue. One of the most common line offenses is for two or three family members to get into line while others are in the restroom, running down fast-passes, checking out at a register, etc. Invariably, the family members left behind want to ride with the rest of their party, and they attempt to push through the line. Not only is this rude, but this is textbook line cutting. If you plan to ride together, enter the line together - period.
Most lines at Disney are not easy to transverse - they are themed, they wind in and out of buildings, etc. To reach people ahead, you have to push past others who are patiently waiting their turn. If you leave the line, you in effect give up your place, and should really only rejoin the line at the end.
I need to join the rest of my party. Refer to the points above - quite simply, don't do this. This is a ploy most often used by teenagers and foreign tour groups, and it is again nothing but line cutting. Sometimes, kind people will allow it, but when a half dozen (or more) individuals try doing this - as is often the case - even the most mellow are often motivated to put a stop to it. Again, if you want to ride as a group, enter the line as a group - no exceptions.