here. Let's extend the scenario further. The Time Patrol universe has either a single mutable timeline or several successive timelines - although these are two ways to say the same thing. See here. This is possible because this fictional universe has more than four dimensions, thus at least two temporal dimensions. Theoretically, it has 4N dimensions.
(We could say either that the contents of three dimensional space change, are mutable, or that a succession of 3D spaces with slightly different contents exist along a fourth dimension. These also would be two ways to say the same thing.)
Anderson's The Corridors Of Time, There Will Be Time and The Dancer From Atlantis are each set in a different universe. However, each of these universes has:
only four dimensions;
therefore, only one temporal dimension;
therefore, only a single immutable timeline.
The Old Phoenix multiverse has many parallel timelines. Thus the Anderson multiverse contains at least:
one universe with a single mutable timeline/many successive timelines;
three universes, each with a single immutable timeline;
one multiverse with many parallel timelines.
It must be difficult, although not perhaps impossible, to enter the immutable timelines.
In my suggested scenario, the Time Lords are the Danellians and the Morlocks-Eloi timeline is a quantum fluctuation within the Time Patrol timeline(s).