What's interesting about The Way Back is how much time they take to establish Blake and his world, plus the only other recurring cast members we meet are Jenna and Vila, and then only briefly. I doubt the new series will be so leisurely.
Well, Terry Nation's original script (which is otherwise almost word-for-word identical to what went out... when he got a first draft right it didn't need any rewriting!) also included Avon and Gan, but only for a couple of scenes aboard the London. Presumably they got dropped because it was cheaper to have a couple of extras sit in those seats.
Similarly, the Federation agent was originally Travis, which makes sense in the big story. Presumably that got changed as it would have locked them into using the same actor later in the season, and they'd have had to pay a retainer to make sure he didn't get booked up with other work....