Short answer: no.
Practically inherited aircraft could be made to fly without the paperwork but not legally. Everybody doing this would loose all his credentials.

Russian Civil Aviation Authority Rosaviatsia offline

https://avherald.com/h?article=4f6a8fd6&opt=0

and an An-124

https://www.cp24.com/russian-plane-s...pace-1.5823860

So Russian airlines are seemingly flying down the FIR borders to Kaliningrad, and the diplomats recently booted out of BRU went the very long way round north of Norway and Sweden, how is this possible from a flight planning/ATC perspective?