Well… crap. For some reason I’m remembered and autologged in Safari, and you’re not. Bugger.
Okay, Plan B. This time start in Part 2. In the bottom left is the “arrow box” as Deb calls it (see screen shot).

Tapping that will get you options (yours will look different); look for “Copy Link” with a chain icon (see next).

Tap that, and you will have a copy of the page URL you can paste. Now you have to find your way to the Part 1 page, tap edit, scroll down to the bottom, throw in a teaser line like, “Want to keep reading? Click here for Part 2.”, select “Part 2”, tap Link (the URL should fill in automatically), tap the Link button, and you have something like:
Want to keep reading? Click here for Part 2.