[Ozzy89]

Actually it does make sense.
Your body has a number of hormonal receptors that will react with the first form of oestrogen that they find (oversimplified). This means that if a weak hormone takes the spot, a stronger one won't.
It's like a parking lot where people park their bikes instead of leaving room for cars. You can park the same amount of vehicles but you'll end up with less people carried there.

So, yeah, don't mix. PM is quite strong. BO is as strong. Adding other weaker hormones doesn't help.

So for example, I wouldn’t take PM with soy milk?