Thanks, Andreas,
I was afraid that because of the matrix calculation I can only see the results and the interim products will be "eaten up".
Does it mean then, once I want to see the contribution of electricity mix to some particular processes, I have to copy and rename the corresponding electricity mix as many times as many processes I want follow and have to use the renamed electricity mix (System process) as a provider. In this case, I will see in the process contribution the share of each renamed electricity mix. Otherwise, the software will just pick up the default provider and draw electricity from the same process.