As of today, the Facebook group "Mondialist, unite!". It shall be a group for Mondialists to exchange topics for a better world. The name and the design of the headers were inspired by the article "Mondialists, unite! The forgotten story of a global pacifist movement" written by the French journalist Isabelle Mayault in The Guardian of 20 July 2017. All interested persons are cordially invited to attend.
Update 1 October 2020:
I have decided at short notice to close this group. In the meantime, I have unfortunately had to realise that it is of no use to the cause. Facebook can be forgotten.