Hi Sergey
>>No problem. It's an interesting exercise but I've a feeling I'd be loading too much logic onto the SQL server anyway...

>I took a closer look at the data and I don't think it's possible to do that with a query. I may be mistaken, though.

Thx for taking trouble over this. I thought the showstopper was being unable to get aggregates in the recursive part of the query - was that your conclusion also?

IAC, I've got a C# recursive function that will do the job and, in practice, it's probably the best approach anyway.

Thanks again,
Viv