If you want absolute control over your fans the best option would be a dedicated fan controller.
Connect two case fans to one header.
That s true for either dc fans or pwm.
Each fan header is rated for up to 1 amp.
This guide will divide in two parts.
One of them is how to connect 4 fans in 1 controller using only your hands and pin extractor or any thin tools like needle.
There is only one caveat.
The easiest and cheapest option is to obtain a y splitter for the 2 fans and control them both with a single fan mate fan mate plugged into mother board then splitter going to the 2 fans.
Second part will be about connecting up to 6 fans using same tools as in first case plus 4 pin molex cable and electric tape or shrinking tube or soldering iron tape.
If the total current drawn by the two fans is less than that rating they can share the header but not if the total current exceeds 1 amp.
This then leaves the other single fan and header conection to the motherboard for control.