offset 16 at bsdlabel step of gmirror config

[Dru]

I've found Ralf's tutorial on configuring gmirror and have read through 
the threads on this list. But I'm still unsure of the bsdlabel step 
when configuring gmirror.

I know partition a is supposed to be offset 16 instead of 0. When I change 
it, I get this message:

partitions a and b overlap!

If I bump up b's offset by 16, that message goes away, but I still have 
this one:

bsdlabel: partition c doesn't cover the whole unit!

I get the same message if I bump up all the offsets (except c) by 16.

Should I:

1. just bump a's offset up by 16 and ignore error messages?
2. bump a and b's offsets up by 16 and assume error message on c is due to
    sysinstall bug and can be ignored?
3. bump up all the offsets by 16 (except for c which shouldn't be touched)
    and ignore error message about c

Dru