Actually, you can test, because everyone is going away. Can you stay out of the pool for the weekend? Keep doing what you've been doing (testing, dosing) and see if the FC stabilizes with no one in your pool. If it does, then bather load is the culprit. If it doesn't, then you'll know it's something else.
Couple other ideas (though these may have been covered, I kinda skimmed your thread).
Are you sure about the age of the chlorine your using? Do you know how to check?
Have you bought it from just one source, one batch? Or have you been getting it from different places?
Even if you're chlorine dates are good, it doesn't mean your chlorine is. A badly handled pallet of chlorine (like left out in the sun for too long somewhere along its delivery route) can trash a brand new palette of chlorine. So if you bought a big supply, and have been using only that, even if the dates are OK, you might have a bad batch. Try buying the next round from a different source, different brand, with freshest dates you can find.
What about the expiration dates on your reagents? I think the TF kits don't have any. So you might be stuck there. When did you buy your kit/reagent replacements? We just solved a mystery testing problem in another thread: it was expired reagents. You might consider buying another batch of the two FC testing reagents, to help rule that out, even if you're sure what you have is not expired. You never know. You'll probably need some anyway, as you burn through what you have now, so that's not money wasted if it turns out the reagents are not the problem.
This is just basic troubleshooting logic. You solve the simplest, likeliest first. If that doesn't work, you have to go after the less likely. Then finally the next-to-impossible.
PS. I was only half-joking earlier. Your little darling is "acclimating" in your pool. I don't know if a 2-year-old can output enough "acclimation" to skew FC, but that seems to be a pretty obvious/likely factor... You'll know after the weekend...
