Here's the trick, and I don't know for a fact if this will work in TT 2017. The last time I pulled this off was back in 2008 or thereabouts.
I assume you've already started the return and thusly imported data from at least one of the QB files. The tricky part that I can't recall how to "make it work" is making the 2nd QB file go to the right SCH C. If things don't go right with the pull of the 2nd file, then you'll probably have to delete both SCH C's and start over. Just let be know and we'll figure it out together.
ALso, my screen shows you're using the online version of Self-Employed, which is basically the same as the desktop version of Home & Business (which is what I'm using). So treat my instructions as guidance, and not as hard fast gospel. The screens, buttons and labels you see, may be different from what I see on my setup.
Under the PERSONAL Tab select the Personal Income sub-tab. If necessary, click the "I'll choose what to work on" button.
The first thing I see in the list of items under the Personal Income (or Wages & Income) tab is called Import Summary. Click the View button to the right of that.
Click Add Other Documents
Scroll down if necessary and select Import From QuickBooks and continue. Work it through and select the QB file to import from.
Repeat the above for the 2nd business, and keep your fingers crossed. I don't recall how the program knows what SCH C to attach things to. So read the screens carefully and completely.
