"Catching Up" Ambleside's Geography Schedule

I've always wanted to use two vintage geography books: Home Geography for the Primary Grades by CC Long and Elementary Geography by Charlotte Mason. They are charming and have a certain something modern books miss. A beauty, perhaps. But I could never figure out how to use them. Until now, because the wonderful people behind Ambleside Online have broken them up by topic, spread across years 1-6 in their new geography schedule.

I'm doing my heavy planning & finalizing in the next two weeks, and I'll have students in years 2, 4, and a combined 5/6/pre-7. So I've been looking at AO's schedule, trying to decide which boy needs what. I've basically decided each boy should review the previous year's topics, and that they will sit in the next younger child's lessons. Clear as mud?

I'll format these as AO does, so one asterisk means term one, two for term two, and (you guessed it) three for term three.

Andrew: Year 2
* Year 1 geography topics: 2 lessons from CM and 3 lessons from Long; 5 total
** Half of year 2 topics, stopping before 'day and night': 4 lessons from CM. 1 from Long; 5 total
*** Finish year 2 topics: 4 lessons from CM; 4 total

David: Year 4
Listen in on Andrew's geography topics.
* Year 3 topics: 10 lessons from CM and 2 lessons from Long; 12 total
** Half of year 4 topics, stopping before 'rivers': 3 lessons from CM and 6 lessons from Long: 9 total
*** Finish year 4 topics: 5 lessons from CM and 4 lessons from Long: 9 total

Jonathan: Year 5/6
Listen in on David's geography topics. All of Jonathan's readings are from Long's book.
* Topics from year 5, terms 1&2: 8 lessons
** Topics from year 5, term 3 and year 6, term 1: 6 lessons
*** Topics from year 6, terms 2&3: 5 lessons

Scheduling
I dislike posting anything about scheduling before I've done it, but my son David has the lion's share of the geography lessons, so I need to be careful with his time. I also need to not over-complicate my schedule, or I will freeze up. I need simplicity. So this is "Plan A", which may fail utterly and require a move to an as yet unknown "Plan B" (which I believe the Mythbusters have patented).

Ambleside's term schedules are 12 weeks each, so the plan* is:

• On odd weeks I will read 1 section from Andrew's list to Andrew & David AND I will read 1 (or 2) sections from Jonathan's list with him.
• On even weeks I will read 1 or 2 sections from David's list with David & Jonathan.

*All plans are subject to change without notice. :P