That’s right, never challenge your kids to do more than they think they can do. Let them do what they want at all times. Praise all their efforts no matter what.
Later on, just don’t be surprised when they give up at the first sign of difficulty with anything they try. That’s a great way to have your basement permanently occupied.
Personally, I think it’s great that this father is taking three weeks off (each?) with his kids. And I have met plenty of competitive women who might relish the challenge to “do in” both the old man and an older brother (I’m the father of one such daughter).
Now to answer the question, the daily mileage would greatly depend on the terrain but I don’t think those daily miles are out of the question as long as all involved are all trained up for them. I assume the weekend hikes have been of a similar distance and have been occuring on a regular basis? If you’e going to do this you will need to be ready to do it.
I assume the plan is NOT to hike 10 days, resupply on the rest day, and then hike 10 more days. It’s pretty hard for anyone to carry 10 days of food. Maybe two rest days? Or, if not stopping, at least arrange for resupply along the route. Is this Mom’s role?
You WILL need to be flexible. As the military folks say, “No plan survives contact with the enemy”.
And tyger deserves a punch in the nose for saying that about another man’s daughter.
Locomotive Breath