>It's not very clear - at all, you restrict the result to Member number = 1
>
>Don't think you need the INTERSECT and the SELECT just after

The Member.Numero=1 is to add support for the result to include at least one invoice client in regards to Member.Numero=1. So, basically, the result of the search has to assure that the invoice clients of those persons would intersect at least one invoice client for a given member.