How to hide from GAL contacts from some OU ?

Good morning!

We use Exchange 2010 SP2.

We have one special OU like 'OU=TestOU;CN=mydomain;CN=com'.

Question - How to exclude contacts from this OU from GAL ?

PS.:

I know one decision with help of GAL Filter throught ADSI Edit like:

- set CustomAttribute like 'secret'

- set GAL filter throught ADSI Edit like (CustomAttribute1 -ne 'secret' -and Alias -ne $null)

It works.

But I don't like this decision very much because that's not convinient: every time to set attribute for some contacts before adding it to these OU or moving from it.

Really more convinient and cool - just to move contact to this OU for GAL hiding purposes or to move it from this OU.

I tried to set GAL filter throught ADSI Edit like:

((RecipientContainer -ne "OU=TestOU,DC=mydomain,DC=com") -and Alias -ne $null -and (((((ObjectClass -eq 'user' -or ObjectClass -eq 'contact') -or ObjectClass -eq 'msExchSystemMailbox') -or ObjectClass -eq 'msExchDynamicDistributionList') -or ObjectClass -eq 'group') -or ObjectClass -eq 'publicFolder'))

((OrganizationalUnit -ne 'mydomain.com/TestOU') -and Alias -ne $null -and (((((ObjectClass -eq 'user' -or ObjectClass -eq 'contact') -or ObjectClass -eq 'msExchSystemMailbox') -or ObjectClass -eq 'msExchDynamicDistributionList') -or ObjectClass -eq 'group') -or ObjectClass -eq 'publicFolder'))

((RecipientContainer -ne 'mydomain.com/TestOU') -and Alias -ne $null -and (((((ObjectClass -eq 'user' -or ObjectClass -eq 'contact') -or ObjectClass -eq 'msExchSystemMailbox') -or ObjectClass -eq 'msExchDynamicDistributionList') -or ObjectClass -eq 'group') -or ObjectClass -eq 'publicFolder'))

But all these variants doesn't work.

Can you help me with such filter ?