присоединение Englisch:

their name and affiliation

An affiliation is an official connection to something. To have an affiliation to something is to be affiliated with it.

For a time, he even gave up his Democratic affiliation.

accession of new member states

a year after Justinian's accession

1926 was the year of Emperor Hirohito's accession to the throne. Poland's accession to the EU. The access of the land took the army less than a week.

It seems it was a gift for the 50th anniversary of Queen Elizabeth's accession to the throne.