The sidestep maneuver is typically used when only one parallel runway has a working ILS but it is preferable to have traffic land on the other one(s) when possible.
In real life, ATC may authorize a standard instrument approach procedure for either one of parallel runways that are separated by 1,200 feet or less followed by a straight-in landing on the adjacent runway.
Aircraft executing a sidestep maneuver will be cleared for a specified approach procedure and landing on the adjacent parallel runway (e.g. “cleared ILS runway 7L approach, sidestep to runway 7R”). After the runway environment is in sight, pilots are expected to commence the sidestep maneuver as soon as possible.
A sidestep to land approach is flown down to the published circling minimums and is considered to be a circle to land procedure. If circling is not allowed (due to terrain, an obstacle, etc.), neither are sidestep procedures.
In Infinite Flight, ATC does not yet have the ability to authorize sidestep maneuvers. However, the pilot may imitate the real-world procedure by tuning to the ILS of either one of parallel runways, flying that down to the published minimums (found on the approach plate), and moving to the adjacent runway when in sight.
Note: Sidestep maneuvers should not be executed within ATC controlled airspace as to not disrupt traffic flow, as we do not currently have the commands accommodate this type of procedure.