Why is installing on UFS even wipes of ALL the irrelated partitions?

I need to install NomadBSD on an UFS partition in parallel to Linux and ReactOS, but the NomadBSD installer does NOT have those options for me, because even installing on UFS still wipes off my everything not relative to NomadBSD …
And i’ve tried bsdinstall and it always fails to connect to anything as for installing the base systems from base.txz or kernel.txz, i suppose that NomadBSD does NOT even have such stuff …
So, please remaster the NomadBSD installer to, installing on UFS does NOT wipe off irrelative partitions, only installing on Z-pools does this.

Probably because the installer isn’t smart enough to detect, find, resize, and move partitions. it is a simple installer that just says “Install me, yay lets do it.”