strawberry@toth.org.uk said:
> I can mount the FreeBSD partitions on the NetBSD side but not the
> NetBSD partitions on the FreeBSD side.

NetBSD and FreeBSD now have different partition IDs
in the MBR.
NetBSD will recognise FreeBSD's ID (165) if the kernel
option COMPAT_386BSD_MBRPART is given. It seems that
FreeBSD does not recognize NetBSD's ID (169). Perhaps
there is a tool to create a temporary in-core disklabel
on the FreeBSD side?
If it is really necessary, you could change NetBSD's
MBR partition to ID 165. You'd have to watch out that
kernel and bootcode have the compatibility enabled.
It is crying for trouble - I can't recommend it.

best regards
Matthias