The first step is to get an inMusic account on www.bfddrums.com.
The next step should be to email your old serial numbers along with your new account info to support@bfddrums.com. Somebody should get back to you.
And if that hasn’t worked, PM the same info to @BFD_Drew on this forum. He’s the product manager.
If you can’t PM him (yet), follow the instructions in this thread to enable PMing. There’s an anti-spam ritual you have to follow first to prove you’re a real person, or at least a respectable emulation of one. How to Private Message in this forum