Help with successfully merging tables / lookup?

Thanks for the fast response and for pointing me down the right track. That worked, however, it has opened another can of worms and I now have a follow-up question if I may..

I added a table of resource names and IDs, a separate one for project names and IDs, and a third table as a timeset for every day of the year (dd/mm/yyyy). I've created all the necessary relatioshships and can now produce the following pivot table which can be drilled down to show per resource below each project.

However, as it is a pivot table with an OData feed i cannot create a calculated field to produce the following desired output. I suspect i need to write a query to do this but do not know where to begin grouping the data by project (and by resources beneath projects) by month, to produce the burn-down of available hours.

Any suggestions on this would be very welcome!

Thanks