@Oscar3 it took us a lot of messages, but finally now I think I get it completely 
the Rel1 has to contain the latest article everywhere
the Rel2 has to be cleaned for every articles, and the latest has to contain a relation to all the previous ones. Correct? 
this would look like this (Article 4 is the latest)
And, with Article 5 being the latest
If that’s correct, I can try and help you. It’s more complex because the current Modules won’t let you add multiple Relations at once; so you need to use “Make an API Call” and you have to build the array of IDs using an Aggregator and a Create Json modules.
Your scenario would look like this (my first module is “create a database item” I used for my tests, but you would have Watch Database Item instead
If you want me to help you on this, we will need to install the Make Dev Tool (here) in your Chrome browser to get an idea about the object names and the different paths, so that we can create the relevant Json document for your Relation 2.
You will find details and instructions for the Make Dev Tool here.
Let me know if you’re ok with this, and we’ll have a look together.
Benjamin