With the marathon 11 weeks after the 70.3, I would train them as separate events. I don’t know your background, but that’s a lot of training stress that’s probably not necessary based on your timeline and goals. You’ll have plenty of fitness from the 70.3 training to lay the foundation for your marathon training afterwards as you’ll be fit enough for a 5-6 hour aerobic event already. Then you just need to finish building your run fitness. Odds are you’ll do some two hour runs in your 70.3 training. And odds are you won’t go much over 3-3.5 hours in your marathon training runs, and maybe less than that depending on goal pace.
With 11 weeks, you’ve got plenty of time to build from 2 to 3-3:30 long runs and get a couple of your longest runs in, even if you take a week or two to recover from the 70.3. You can still bike or swim for recovery between your key run sessions if you want to.
Almost 9 months is a long, long time to run marathon volume, especially when a good portion of that time you’re training for another event altogether. Earlier this year, I raced my A 70.3 and got a good result. I scheduled a C type half marathon 8 weeks later where, building off my fitness from the 70.3, I wanted to go after a PR on a flat fast course. Turned out, after my 70.3, I had little desire to train for the half marathon. I can’t imagine how I would’ve felt with that much more run volume already banked. So even if you physically can handle that training load - and then build off of it - I think most people would struggle to remain motivated.
All due respect to the plan the user above spelled out - which obviously worked for them - remember that they weren’t training for a triathlon while doing that plan. If they skipped strength or skipped the bike, it had no impact on their goal event. You’re going to be training all three sports for a competition, doing a lot of two a days, and if you skip a lot of workouts, your performance at your goal event will suffer for it.