question about 144 hour visa

Jason, you mean you will travel like US-Shanghai-HK, or HK-Shanghai-US, actually, as long as your layover time in Shanghai is less than 144 hours, both routes are eligible for the 144 hour free transit. You need to make sure that, after transiting in Shanghai, you will fly to a third country or region different from the last one you fly from.

I mean she's flying from the US to Shanghai but her flight stops in Hong Kong before coming to Shanghai and then we are going to Hong Kong after.

If so, you cannot use the free transit in Shanghai because after stopping in Shanghai, you fly back to HK. You should apply for a tourist L type for your entry to mainland PRC.

What if I bought her a ticket to Macau just to get the visa? Would that work?

If she flies to Macau after transiting in Shanghai, she can enjoy the free transit in Shanghai.

What if I just buy the ticket to Macau just to get the visa but don't use it and just fly back to Hong Kong when we are done in Shanghai?

It's fine. Don't worry.