That already exists for serious cases. The clue is in "serious".
Indeed joint working arrangements do exist. One of the benefits of such an agreement to pool resources is it cuts bureaucracy and duplication of effort and costs.
Unfortunately it doesn't just happen automatically, it has to be negotiated and agreed.
I wonder why you consider a case concerning a missing child isn't a "serious" one. Would it make a difference if her name didn't end in McCann?
**Snip
Mrs McCann said she was particularly frustrated that police in Portugal had so far ruled out a joint inquiry with their British counterparts.
"As a parent, I find the slowness of action in Portugal really hard to take. I find it quite distressing," she said.
"Even though we're seven years down the line, waiting weeks or months, particularly for letters of request to be processed basically... it is frustrating.
"I suppose I do struggle with the fact. Please work together."
'Parallel investigations'Mrs McCann said she had not been given a reason why a joint team had not been set up.
"To us, it makes sense that the two police forces should work together, to have a more streamlined approach to avoid duplication and basically to progress the investigation at a faster pace," she added.
Her husband Gerry said: "What is very, very clear is that there are lots of lines of inquiry and a lot of further work needs to be done in Portugal.
"The Met can only do so much with the information that they have."
Mr McCann said it was a "big step forward" that the Portuguese investigation had been reopened but admitted the bureaucratic process was causing delays.
"The concern that we have, and I think also that the Metropolitan Police have, is that at the minute, there's almost parallel investigations going on, which doesn't make sense," said Mr McCann.
"We're not quite sure why there's resistance to the joint investigation team, because clearly resources in Portugal is an issue and this would be one mechanism by which they could have additional funding."
http://www.bbc.co.uk/news/uk-27239149