Dean,
For the 9 week-gap between 09/13 and 11/15, I recommend taking one week off of training, then load the plan again with an end date of Nov 15, starting in Week 11 of the plan and completing the final 8 weeks.
I would follow this same pattern of training for 5-8 weeks between Marathon plans as well.
OK, to be honest, in a perfect scenario I would write a custom plan for the athlete to cover those 5-9 weeks based on their performance from Marathon #1 and addressing their strengths and weaknesses. For example, the last 8 weeks of the 80/20 marathon plan will significantly reduce Zone 4 work. But what if that is what the athlete still needs? If they just nailed Marathon #1, I’d be more focused on maintenance. If they struggled at mile 16, I’d be more focused on number of 18+ mile runs.
But, if you are using a pre-built plan, my recommendation will get you 95% of the benefit for 1/3 of the cost.
David