A few things from a fellow 50/50 parent, rec athlete...
Great job on doing what it takes to get to parent your daughter min 50%. Shows you have your priorities straight. Too bad there are not more parents like you out there. I am sure you maximize the time you have with your daughter as well. I know I do with my son.
For the training, make sure you mix it up. Train multiple ways. Ensure you mix speed work with endurance work, and keep up the core and some resistance training.
For the race, DO NOT worry about the location or pace of others in your age group during the race. Their is plenty of historical data (repeatable) to show what sort of time will get you to your goal. You have found this data already. Race against the data and your goal, not others in our group. Do you really know anything about your fellow competitors strenghts? Probably not, so don't pay any attention to them. Your goal should be based on a finishing time that nets you a placing you are hoping for. This will also help you keep your goal realistic and achievable, two of the most important factors of goal setting. Race your race, not anyone elses.
Why track someone (you don't know) through the swim and bike. Later you find out they were a collegiate swimmer and rode in a cylcing club but can't run worth a darn. You waste energy trying to pace them only to get spent and realize they can't run..... Again, pick a finishing time goal, and stick to it. Keep and an eye on your event times and segment times, know where your strenghts are and beat your goal.
Another thing to consider. When push comes to shove out on the course, it is really mind over matter. That is something you have already demonstrated being able to do. With the sacrifices and choices you made to do "what is right" when it comes to your child you will have no trouble overcoming the mind game of meeting your goal on race day. You know you can complete the events and you will.
I am training with my (almost) 11 year old son for his second triathalon. We train his mind as much as his body when we are out training.
Can't wait to read your post where you beat your finishing time goal!