Question about dual booting Windows and MacOS Big Sur on the same hard drive where Windows is already installed with OpenCore

I am trying to install MacOS Big Sur alongside with Windows 10 and the most important for me is to not remove Windows. I am asking because I want MacOS and Windows to be on my main hard drive and bootloader to be OpenCore. Is this possible? Because everyone who I have asked before tell me that I should install MacOS Big Sur first, but I watched some videos where people have dual booted the both operating systems on the same hard drive with OpenCore.