Lost FreeBSD slices (labels?) after NetBSD install -- please help!!

[Snow Mountains]

Hi,

People, I have FreeBSD install on 80G disk that looked like this:

ad1s1 ~ 2.4G
ad1s2 ~23.0G
ad1s3 ~19.1G
ad1s4 ~38.0G, FreeBSD partition, sliced like this:
------------------------
ad1s4a /     (507630 1K-blocks)
ad1s4b swap
ad1s4d /var
ad1s4e /tmp
ad1s4f /usr

First three partitions are former fat/ntfs that I emptied, transformed
to FreeBSD's ufs2 and used as FreeBSD storage. I used boot0cfg and my
boot menu looked like this:

F1 DOS (although nothing were installed in F1-F3, just ufs2 data)
F2 DOS
F3 DOS
F4 FreeBSD

Today, however, I decided to try a small NetBSD install on small
ad1s1, I thought I could do no harm if I tell it to install itself
onto first partition. So I passed through install, carefully checked
partition1 (on wd0 disk according to it) for mark 'new fs', and sliced
it did like this:

wd0a / (around 550M)
...
wd0e /usr
(total ~2,4M, as described above)

and left all other options (BSD labels etc.) as defaults. NetBSD
installed and booted, menu looked like this:

F1 BSD
F2 DOS
F3 DOS
F4 FreeBSD

However, FreeBSD is now unbootable!!! Then I loaded FreeSBIE (FreeBSD
6.2 live CD), tried 'boot0cfg -B /dev/ad1' (also with '-d 0x80'), but
no help! Then I realized that ad1s4 slices are lost. This means:

A) from FreeSBIE, there is only /dev/ad1s4, no a,b,d,e,f. If I do this:
FreeSBIE# mount /dev/ad1s4 /mnt/ufs.4
this is former / (ad1s4a) and is of its size (~507M).

I can't reach other slices! However, it gives me hope that NetBSD's
slices are also invisible, although working from within itself:
FreeSBIE# mount /dev/ad1s1 /mnt/ufs.1
gives also small NetBSD's / (its wd0a), not /usr etc.

B) From NetBSD:
FreeBSD's ad1s2  -> NetBSD's wd0f (readable, data ok)
FreeBSD's ad1s3  -> NetBSD's wd0g (readable, data ok)
FreeBSD's ad1s4a -> NetBSD's wd0h (just /, 507M, readable)
others (ad1s4 d-f), containing /usr/home are lost!

Please help me to recover my FreeBSD system. If I lost my data (ok, I
understand they are buried, not erased), please tell me that gently.
:-(

many thanks in advance
Sergi M