I'm Portuguese and I think it's shameful for PJ to realize what they did not do, how they failed in handling the case from the beginning and how the case can be now solved by other police force, 14 years later.
Unfortunately it will not be a suprise if they are still crystallized in the pathetic GA theories and "believing" CB is not the man. Unfortunately it will not be a suprise if they insist, presumptuously and spitefully, that they do not and will not cooperate. Unless BKA opens the game and share the evidences. But will they help in speeding up the process?! Will they still not want to take the final honours? Or discredit the German pieces?!
I want to be wrong and believe there will be no more obstacles to the investigation and final outcome.
It's all a bit more complex though - and depends on what PJ is asked to do.
For instance, if it is more searches, cause for warrants etc is needed, which means they need to be provided with at least some intelligence. That is not unreasonable, and is legally important.
For german police to come over in an operational role, after the Redwood fiasco, there is no way PJ will agree to do that without some reasonable basis.
None of this should be surprising. BKA can't go searching around Germany without cause either. There is oversight.
From the legal point of view of Portugal, this case was archived with no clear evidence of a crime having been committed, or if one was, no specificity of which crime. Even the original summary held out the possibility of death by accident (i.e not a crime).
So I guess it should come as no great surprise that PJ would require either some specific intel to justify resource and on ground searches, or some other information on the nature of offending.
What I think they won't do, is go on a fishing expedition to find that evidence based on a mere theory.