Your board has six fan headers. The CPU_Fan2 header (three pin) is supposed to be synchronized with the CPU_Fan1 header, even if you use a four pin PWM fan on it, like the Blade Master. Instead of the fan splitter, try the two CPU fans on those two headers.
The fan headers on most boards (like this one) allow up to 1.0A of power. Check the label of your fans to be sure they are below that. Some fans use more power than their specs/label, but your CM fans should be fine.
If the CPU_Fan2 header does not control the second fan's speed, you should be able to use the splitter with the two Blade Master fans on your '212, which comes with a Blade Master fan, as you know. As long as the two fans don't use more than 1.0A total, you should be fine.
Using the PWR_Fan header is fine, but you cannot control its speed, any fan connected to it will run at full speed.
Your four in one pack of CM fans should be the Sickle Flow fans. They are rated at 0.37A, so are not stressing the fan headers.