Exchange 5.5 GAL

The charity I work for has approximately 20 users who are located within other organisations (primarily councils and government departments throughout the UK) and are providied with email addresses by their IT departments. Our global address list is populated with their email addresses by the use of Custom Recipients - no surprises so far.

Is there anyway that I can make our GAL available to these remote users, obviously their GAL contains the users within their domain and they are constructing their own address books for our organisation of over 150 users??

The only solution I have is to create a PAB from our GAL and then send them the PAB?

Many thanks in advance,