Suppose streams A and B both are seeded from baseline bl_C_5 of some stream C. From there parallel developments goes in A and B and some point the baseline at A is bl_A_3 and in B is bl_B_6. At this point is it posible to deliver bl_B_6 from B to A so that A will now contain an exact copy of bl_B_6 (without being merged with bl_A_3)? In other words is it possible to completely overwrite a stream with delivery operation? If not, is there any other way or command for achieving this?
A "copy merge" isn't supported at the deliver operation (it can be supported at the type level, by associating a "copy-merge" policy, but that isn't practical when you want to merge everything)
One way to quickly do a "copy-merge" is to:
clearfsimport -rmname from a view on the source Stream to the destination view (see this question for instance, and man clearfsimport): you will get a mirror image of Stream B on stream A.