I have developed many-to-many relationships by using a dedicated form and view
for containing the relationship data. A relationship record is created per
relation between the two related documents, containing their id's.
When e.g. the one of the documents are opened, a search finds a collection of
the relationship-documents, and another search finds the needed data in each
related destination document. The data is just shown on the opened document.
A maintenance code is creating and deleting the relationship documents, keeping