As BAM is on one central place and has the capability of "attach/detach" projects

The Idea of a BACKUP project was born

That is:

I attach to a client two projects

The principal one, I want to crunch how much as possible

And the the secondary project that I want to crunch (on this client),
only IF the principal one has no work ...

How about BAM managing this, automaticaly :?:

When no work from pricipal project, BAM automatically attaches the secondary project to that client

When there is work again for the principal one, BAM automaticaly sets the secondary one to "no more work"

Later ...,

When the secondary project Queue is emply ... BAM automatically detach the secondary project

Please, comments about this idea.

I don't think that is something BAM can do? As far as I know it can't monitor the work you have in the BOINC queue as all it does is access the parts of the projects it is allowed to, to enable to detach/attach and change preferences.

Your idea would possibly need a full BOINC & Server re-write?

True. BAM cannot control the "no new work"/"allow new work" and cannot monitor the flow of workunits (for now). But if the devs over at Berkeley implement that in both BOINC Manager and server code then it'll be possible.
Anyway very nice idea

Hee hee more chance of getting blood out of a stone then that happening at the moment!! lol

I too love the idea, but I suppose we will have to wait for the joint effort of Berkeley & WCG now, that will probably be the next big thing in BOINC

Set the resource share on the main project to 1000 and on the backup project to 1. This will not achieve exactly what you want but it's a good approximation.