Words from “Christmas sleighride”

Here I will post a series of (mostly) simple challenges to amuse you in the run-up to Christmas. I'll try to post one each weekday.
DDRM
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Joined: Mon 02 Apr 2018, 18:04

Words from “Christmas sleighride”

Post by DDRM »

This is similar to challenge 4, but there are multiple copies of some letter: for example there are 3 “s”s. “Words” may contain such duplicates, but replacing one S with another does not make a new “word” – so “sat” can only appear once in the list.

An additional rule is that “sh”, “th”, “ch” and “gh” and “st” can (but don’t need to) count as a single letter – so “Christmas” and “sleighride” are now valid words, despite having three consecutive consonants.

Given these constraints, how many "words" can be created?