Hi Mojca,

Many thanks for your attention and insight.
I tried what you said and I put all the instructions you gave in a  
file I am sending you: it is meant (once all the steps work fine) to  
become a file
updating-context.sh
which could be excuted in a Terminal window upon saying
	sh updating-context.sh

Now mkii can be updated following your instructions after fixing some  
chmod issues.
If the remaining problems described in the attached file are solved in  
such a way that a non specialist like me can uderstand, then I'll put  
the script and the explanations of the commands on the wiki.
I presume it will be helpful for others too…

Thank you for your time!
Best regards: OK