@mercurhyo
If it helps I did find a way to install BGRABitmaps, BGRAControls, BGRAControlsFX under FPC > 3.0.4:
1. If installed, uninstall BGRABitmaps, BGRAControls, BGRAControlsFX, delete all folders
2. Install BGRABitmap, rebuild Lazarus, delete the lib folder(it's located at: $(BGRABitmap_Folder)\bgrabitmap\lib
3. Install BGRAControls, rebuild IDE
4. Delete the BGRABitmap lib folder again
5. Install BGRAControlsFX, rebuild IDE
Obviously there is a bug, which make BGRAControls/BGRABitmap mutually exclusive in a higher version of FPC, or at least very difficult to install the packages at the same time. Hopefully the bug will be fixed soon. Since the issue has nothing to do with OPM(the same bug is reproducible with manual install) there is little I can do about it. I really don't like to debug/modify other people packages.
PS: Thank you for the feedback.