I've combined OTA & sat for 18 years now with a diplexor with no problem. They operate on separate frequencies, so that won't cause a problem.
However, OP, I'm almost positive your drawing won't work because you can't easily split a DBS signal. I don't have time to draw it up right now, but my OTA antenna feeds an amp (to make up for splits & line loss), then hits a splitter. Each output of the splitter feeds one side of a diplexor. The other side of the diplexor is fed direct from the LNB. Single line out of the diplexor to where the TV is and hits another diplexor. That separates the sat & ota. Sat goes into the receiver, OTA goes to another splitter, which feeds both sat rx & the TV.
So I have four diplexors (two for each sat receiver, one to merge the signals and one to separate) and three splitters for OTA (one at my "head end" and one each at the TV/Sat receiver).
Hope this makes sense.