I. Master List of Timelines Whose Likenesses Appear in Any Capacity
(by order of appearance)

Twilight’s home / Versus Miasmus - Reflections

Fallout: Equestria verse / Fallout: Equestria - Kkat

Starlight's home / Twilight’s refuge - Reflections

Above the Crystal Empire - Reflections

Sweetie Honey verse / Warrior of Love, Sweetie Honey! - CrowMagnon

Pandoraverse / Baby Sister - Lopoddity

Quiververse / A Shimmering New Year - EchoWing

Littleverse / Sunset’s Little Twilight - PoisonClaw

Restaurant/hospital of the future - Reflections

Crystal Faire’s home / Epicenter - Reflections

Sunset’s home / Crystal Ball-verse CCCXXIV / Substitute - RQK

Experimental timeline II: Sunset concurrently-crystallized - Reflections

Experimental timeline III: Starlight concurrently-crystallized - Reflections

ES Harmony-verse / Experimental timeline V: Relativity / Harmony Among The Stars - tom117z

Experimental timeline VI: Inanimate object concurrently-crystallized - Reflections

Experimental timeline VII: Second spell - Reflections

Collided timeline α - Reflections

Chrysalis’ home / Collided timeline β - Reflections

Past Sins-verse / Collided timeline γ / Past Sins - Pen Stroke

Metallixverse / The Metallix Project - RedRandom

Weatherponyverse / Weatherpony - HapHazred

Floydverse / My Name Is Floyd Damn You! - shagohad12

Reign of the Storm King - Reflections

Seedsverse / Seeds of Darkness - EStories

Dangerous Business-verse / It's a Dangerous Business, Going Out Your Door - Jetfire2012

Equestria Now!-sighting on the grassy hill / It's All A Little Strange To Me - Essay Jay

Base camp / Crystal Ball-verse MMLXXVII / Feedback - RQK

Codeverse / Collapsing timeline / The Celestia Code - iisaw

Morning Glory-verse / The Moon, The Flower, and The Door - Bucking Nonsense

Celiaverse alternative / Small Scale - Twinkletail

Assassinverse / Collided timeline 𝛿 / The Assassination of Twilight Sparkle - Rated Ponystar

Collided timeline ε - Reflections

Skirmish in Cloudsdale - Reflections

Skirmish in Las Pegasus - Reflections

Skirmish in Griffonstone - Reflections

Skirmish in Klugetown - Reflections

Skirmish in Canterlot - Reflections

Final destination timeline MMXVIII - Reflections

II. Short List of Timeline Mechanics and States
Terms:
Threaded - A state in which a set of timelines are wound together to act as one single timeline; wherein a stretch of spacetime is constant across all the timelines for the duration in which they have been threaded together.
Unthreaded - A state in which any two timelines are distinct; not threaded.

Crystallized - A timeline’s hardened state. Signifies areas which Crystal Faire has visited. Crystallized portions cannot be changed under any circumstances.
Uncrystallized / hazy - A timeline’s default state; perfectly mutable. Hazy areas which exist after crystallized areas fluctuate as crystallized portions expand.
Semi-crystallized / shiny - Another hardened state which cannot be changed under any circumstances. Always precedes a crystallized line segment.
Concurrently-crystallized / solid and viscous - A state in which a timeline and its divergent set is occupied by something or somepony multiversally significant. All probabilities thread into one single timeline should Crystal Faire visit any moment within the set.
Quasi-crystallized / almost crystallized - A state which represents time-dependent events, such as time travel. Typically, isolated segments of the line which are in this state are cannot be accessed by Crystal’s travel ability.

Filter - Something which Crystal Faire uses to manipulate the way in which she sees timelines; in particular, filters automatically group timelines which meet specific criteria so that they appear as one single timeline and, should Crystal decide to visit them, automatically threads them together.

Further rules:
Timelines are infinitely diverging between one instant and the next instant. For some timeline, there are infinitely many branching off it in the next moment, and another infinitely-many branching off of each of those infinitely-many in the following moment. This makes the multiverse like a tree. One interpretation may present this as sets of timelines unthreading with each passing moment (thus leaving the total amount of timelines for all time as constant).

All timelines branch off from a singular moment: the night after King Sombra’s defeat. All events up through that moment are constant across the entire multiverse.

Alternate realities like Canterlot High, the mirror universe, and anything which may physically connect to Equestria in any sort of way is included within the set of realities which constitute one single timeline. Of these, Crystal Faire currently may only see the reality which Equestria sits in.

Crystal Faire may only use the travel ability to travel to locations that she can see. Per above, this means the travel ability may only be used to travel to locations within the reality which Equestria sits in, but it may be used to travel from any location.