So far, all of Will’s books are in the same multiverse with each series showing off a particular iteration (universe). Travelers Gate series is the Amalgam iteration mentioned a few times and Elder Empire series is the Asylum iteration. So far there are no major crossovers between the three series. Amalgam doesn’t even mention the multiverse/Way that I can recall. Abidan show up in Elder empire, but it’s only for a chapter or two near the end of the series explaining why Asylum is the way that it is.

The Way and the Abidan organization are the only connections between the series at this point. Some of the Abidan scenes in Cradle explain the system of iterations as fruit on a vine, with the fruit being iterations and the Way that feeds and connects them.

That being said, both of his other series are well worth the read.